what oil weight to use?

[Guest Anonymous]

right now i am using 10-30w, but thinking of going synethetic. how bout it? what oil weight does everyone use? what is the popular choice?

 

 

i have a fairly stock 350 sbc.

[Guest dambro]

I had good luck switching to a blend. My motor(also relatively stock 350chev) seemed to rev easier.

[Tim240z]

MY LT1 Factory Service Manual says to use 5W30 ONLY, so I'm using 5W30 Mobil 1.

Tim

[Guest Anonymous]

Hey StocktonZ;

Synthetic oils a good way to go, not only in the engine, but the trans and rear end also like the slippery stuff. I run a 370HP Chevy 350 in my 72 240Z with a 700R4 trans that was all re-built before installation. Break-in on regular oil then switch to synthetic. I run 15-40 in the engine, synthetic trans fluid and 75-90 synthetic in the rear end. The engine runs cooler, I get about 3-5 mpg better on the highway( not that it matters) and the time between changes is longer. I changed at 3000 miles and the oil looked new!!!!! My two cents, synthetics are the way to go!! 8)

[Guest Anonymous]

i forgot to mention, my engine has approx 1000 miles on it. i should use 15-40 synthetic still? what's better, multi blend or just plain synthetic?

[Guest Anonymous]

This forum stuff is great;

I would put another 1000 miles on the car, on the highway, verying speeds every 20 minutes( try and keep in reasonable )

I use Chevron because I get a screamin deal, but reasearch shows next to no difference between brand name stuff. I live up in B.C. and run the car in the summer, a little cooler than Stockton, but I think 15-40 would do you fine. Next time in Stockton, I hope t5he coffee's on!!!! 8)

[Guest Anonymous]

OPPS;

Forgot to mention, full synthetic is the best, even though it is a lot more expensive. If blend is what you pocket book tells you to buy, rest assured it's better than regular oil, and , no, I don't work for an oil company 8)

[Guest Anonymous]

DELETE

[Guest the_dj]

Full synthetic like mobil 1 will save money over time. In a well running engine, you can get upwards of 8K miles before a change. It's more expensive, but if it lasts 3 times as long, then it looks even more promising.

 

I run 10/30 Mobil 1.

[grumpyvette]

your engines clearances determine the correct viscosity of oil to use!

 

engine oil preforms best in the 230f-240f temp window, keep in mind mineral base oil tends to break down at temps over 250f-260f over long periods so synthetic oil might be an advantage,oil temps below 215f are a very big NO-NO in that the engine can,t burn off any water vapor in the oilpan/block and corrosion can be a problem. coolent temps durring hard running should not exceed about 220f and 210f is better, but lower temps than 200f tend to cause a slight power drop, now you might look at those temps like I did and say they are all just a little to high! well SMOKEY YUNICK doing testing for G.M. was spending thousands of dollars in dyno testing to find out! Ill take his dyno results over guessing any day!. yes I know, coolent temps of 160f-180f tend to help limit detonation problems, but your giving up a small potential in hp at least in theory

youll need to use the MINIMUM viscosity of oil that maintains about 20lbs-25lbs of oil pressure at idle speeds when the oils up to at least 200 degs f, with proper bearing clearances that tends to be close to 10w30 and ID HIGHLY RECOMMEND MOBILE 1 OIL and A GOOD FILTER CHANGED OFTEN matched to a well designed oil pan and windage screen

 

IVE POSTED MOST OF THIS BEFORE BUT IT FITS HERE AS A SOURCE OF INFO FOR THE NEWER GUYS

if you have the chance go an get a better baffled higher capacity oil pan that is engineered to control the oil supply better, NOTICE not once did I say spend tons of money, please pay attention while I prove my case!

 

http://www.melling.com/highvol.html

http://www.melling.com/engoil.html

 

ok lets look at a few things, pressure is the result of a resistance to flow , no matter how much oil is put out by the oil pump there is almost no pressure unless there is a resistance to that oil flow and the main resistance is from oil trying to flow through the bearing surface clearances and once the pumps output pressure exceeds the engines ability to accept the oilflow at the max pressure the oil return system/bypass spring allows the oil circles back through the pump ,now the amount of oil flow necessary to reach the furthest parts in the engine from the oil pump does not go up in direct relation to rpm, but it instead increases with rpm at a steadly increaseing rate that increases faster than the engine rpm due to centrifugal force draining the oil from the rods as they swing faster and faster since energy increases with the square of the velocity the rate of oil use goes up quite a bit faster due to the greatly increased (G-FORCES) pulling oil from the rod bearings over 5000rpm going to 8000rpm than the rate of oil flow increases from 2000 rpm to 5000rpm (the same 3000rpm spread) and remember the often stated (10 lbs per 1000rpm)needs to be measured at the furthest rod and main bearing from the pump not at the pump itself, next lets look at the oil flow itself, you have about 5-6 quarts in an average small block now the valve covers never get and hold more than about 1/3 to 2/3 of a quart each even at 8000 rpm (high speed photography by SMOKEY YUNICK doing stock car engine research with clear plastic valve covers prove that from what Ive read) theres about 1 quart in the lifter gallery at max and theres about 1 quart in the filter and in the oil passages in the block, that leaves at least 2 quarts in the pan at all times and for those that want to tell me about oil wrapped around the crankshaft at high rpms try squirting oil on a spinning surface doing even 2000rpm (yes thats right its thrown off as fast as it hits by centrifugal force, yes its possiable for the crankshaft WITHOUT A WINDAGE SCREEN to keep acting like a propeler and pulling oil around with it in the crank case but thats what the wrap around style milodon type windage screen is designed to stop)the only way to run out of oil is to start with less than 4 quarts or to plug the oil return passages in the lifter gallery with sludge or gasket material! now add a good windage tray and a crank scrapper and almost all the oil is returned to the sump as it enters the area of the spinning crankshaft! forming a more or less endless supply to the oil pump, BTW almost all pro teams now use DRY SUMP SYSTEMS WITH POSITIVE DISPLACEMENT GERATOR PUMPS that are 3,4,or 5 stage pumps each section of which has more voluum than a standard voluum oil pump because its been found total oil control is necessary at high rpms to keep bearings cool and lubed

 

NOW I POSTED THIS BEFORE BUT IT NEEDs REPEATING

ok look at it this way,what your trying to do here is keep an pressureized oil film on the surface of all the bearings to lube and cool them and have enough oil spraying from the rod and main bearing clearances to lube the cam and cylinder walls/rings. now a standard pump does a good job up to 5000rpm and 400 hp but above 6000rpm and 400hp the bearings are under more stress and need more oilflow to cool and because the pressure on the bearings is greater you need higher pressures to maintain that oilfilm.lets look at the flow verus pressure curve. [color:"red"] since oil is a liquid its non-compressable and flow will increase with rpm up to the point where the bypass circuit starts to re-route the excess flow at the point were the pressure exceeds the bypass spring pressure. but the voluum will be equal to the pumps sweep voluum times the rpm of the pump, since the high voluum pump has a sweep voluum 1.3-1.5 times the standard pump voluum it will push 1.3-1.5 times the voluum of oil up to the bypass cicuit cut in point,that means that since the engine bearings leakage rate increases faster as the rpms increase because the clearances don,t change but the bleed off rate does that the amount of oil and the pressure that it is under will increase faster and reach the bypass circuit pressure faster with the high voluum pump. the advantage here is that the metal parts MUST be floated on that oil film to keep the metal parts from touching/wearing and the more leakage points the oil flows by the less the voluum of oil thats available for each leakage point beyond it and as the oil heats up it becomes easier to push through the clearences.now as the rpms and cylinder preasures increase in your goal to add power the loads trying to squeeze that oil out of those clearances also increase. ALL mods that increase power either increase rpms,cylinder preasures or reduce friction or mechanical losses. there are many oil leakage points(100) in a standard chevy engine.

16 lifter to push rod points

16 pushrod to rocker arm points

32 lifter bores 16 x 2 ends

10 main bearing edges

9 cam bearing edges

16 rod bearing edges

2 distributor shaft leaks

1 distributor shaft to shim above the cam gear(some engines [/color] that have an oil pressure feed distributor shaft bearing.)

so the more oil voluum the better,(AS LONG AS ITS TOTALLY UNDER CONTROL ON BOTH THE PRESSURE AND RETURN/SCAVAGEING SIDES OF THE SYSTEMchevy did an excelent job in the design but as the stresses increase the cooling voluum of the extra oil available from the larger pump helps to prevent lubracation delivery failure, do you need a better pump below 5000rpm or 400hp (no) above that level the extra oil will definitely help possiable deficient oil flow and bearing cooling and a simple increase in pressure does not provide a big increase in voluum that may be necessary to keep that oil film in the correct places at the correct voluum at all times.the stock system was designed for a 265cid engine in a passenger car turning a max of about 6000 rpm but only haveing the stress of under 300hp transmitted to the bearings, Im sure the orriginal designers never thought that the sbc or bbc would someday be asked to on occasion hold up to 450-800hp and 6000-8000 rpm.nore did they forsee valvesprings that placed 500lbs and up loads on the lifters and the use of over 9 to 1 compression ratios in the original design so the oil voluums and pressures necessary to cool those valve springs and bearings at those stress levels were never taken into account for that either.

 

Continued (oil Pan/pump)

the oil pump can only pump as much oil as the engine clearances allow at the max pressure that the oil pump bye -pass circuit will allow, and no more. for your idea to be correct (which it could be under some conditions)the oil flow through the engine clearances would need to be so great that the pump turning at 3500rpm,7000rpm engine speed(remember the pump spins 1/2 the speed the crank does)and most likely pumping at max pressure could lower the oil level to the point that the pick-up becomes uncovered or a vortex as you call it forms and the pump starts sucking air.

 

 

now under hard acceleration it is very possiable for the pickup on ANY oil pump to to become uncovered in a oil pan that has less than 5qt capacity and with no oil control baffles as the oil rushes to the rear of the oil pan if the pick-up is located in mid pan or under hard brakeing if the pick-up is located at the rear of the pan on a non- oil baffle controlled pan.

 

I will grant you that it is possiable for ANY oil pump to pump a good amount of oil into the lifter gallery at high rpms IF THE OIL RETURN PASSAGES IN THE HEADS AND LIFTER GALLERY ARE BLOCKED, preventing its normal return to the crankcase

 

, but running a high volume oil pump will have little or nothing to do with how much oil is in the pan if the engines drain back holes are clear and your useing a milodon style windage screen. I have several times had that same complaint about lack of oil pressure under acceleration but it is caused by a non-baffled pan or the pickup mounted so close to the pan bottom that the pump cant get a good intake flow, if you carefully check youll find that on a dyno runs it seldom happens,because the oil is constantly removed by the windage screen is returned to the sump, most of the oil pumped into the system exits at the rod and main bearing clearances or at the cam bearings and from the lifter bores lower ends, its not the constant oil flow or lack of oil into the rocker arms that has the big effect on total oil flow as SMOKEY YUNICKS PHOTOGRAPIC RESEARCH PROVED YEARS AGO,its the oil flowing from the bearings and lifters and that oil flow is quickly returned to the sump by a windage screen scrapeing it off the spinning crank and rods as the spinning assembly passes over the windage screen. in effect most of the oil in an engine works like your timeing chain in that it constantly cycles top to botton and back never getting higher than the cam bearing lifter area.

 

[color:"red"] now what does quite frequently happen [/color] is that the guys installing a high volume oil pump just swap out the standard pump, reinstall the stock or simular pick-up and bolt on the pan with the pick-up in the stock possition on the oil pump. the stock pick-up is mounted about 3/8" off the pan bottom,the high volume pump is normally equiped with impeller gears about .3 inches longer than stock, the high volume pump body is that much lower in the pan, resultting in the pick-up being only about 1/8" from the pan bottom. the result is that on a normal chevy oil pump pick-up this leave a space of about 1/8" x 2.5" for oil to flow into the pump. at low rpms this works but as the rpms climb the pick-up that can,t get any oil to pump cavitates as it spins and fails to pump oil, result oil pressure drops untill rpms are lowered no matter how much oil is over the pick-up. simply checking to make sure that anout 1/2" of space is under the pick-up when the pan is installed cures that problem (a simple trick is to weld a 1/2" thick nut to the oil pump Pick-up base and test fitting the pan BEFORE WELDING THE PICK-UP TO THE PUMP BODY)

 

what it comes down too in every case that Ive looked into so far is a improperly positioned pick-up or a non- baffled oil pan without a windage screen or less than 5 qts of oil in the system, not a problem of all available oil being pumped into the lifter gallery and valve covers like some people would like you to think.

 

the MELLING COMPANY HAS THIS TO SAY

 

Most of the stock automobile engines are designed to operate from idle to 4500 RPM. The original volume and pressure oil pump will work fine in this type of application. As the demands on the engine increase so does the demands on the oiling system and pump.

The oil pump's most difficult task is to supply oil to the connecting rod bearing that is the farthest from the pump. To reach this bearing, the oil travels from three to four feet, turns numerous square corners thru small holes in the crankshaft to the rod bearing. The rod bearing doesn't help matters. It is traveling in a circle which means centrifugal force is pulling the oil out of the bearing.

 

A 350 Chevy has a 3.4811 stroke and a 2.111 rod journal. The outer edge of the journal travels 17.5311 every revolution. At 1000 RPM, the outer edge is traveling at 16.6 MPH and 74.7 MPH at 4500 RPM. If we take this engine to 6500 the outer edge is up to 107.9 and at 8500 it is 141.1 MPH. Now imagine driving a car around a curve at those speeds and you can feel the centrifugal force. Now imagine doing it around a circle with a 5.581, diameter.

 

The size of the gears or rotors determines the amount of oil a pump can move at any given RPM. Resistance to this movement creates the pressure. If a pump is not large enough to meet the demands of the engine, there will not be any pressure. Or if the demands of the engine are increased beyond the pumps capabilities there will be a loss of oil pressure. This is where high volume pumps come in; they take care of any increased demands of the engine.

 

Increases in the engine's oil requirements come from higher RPM, being able to rev faster, increased bearing clearances, remote oil cooler and/or filter and any combination of these. Most high volume pumps also have a increase in pressure to help get the oil out to the bearings faster.

 

That is what a high volume pump will do. Now let Is consider what it will not do.

 

It will not replace a rebuild in a worn-out engine. It may increase pressure but the engine is still worn-out.

 

It will not pump the oil pan dry. Both solid and hydraulic lifters have metering valves to limit flow of the oil to the top of the engine. If a pan is pumped dry, it is because the holes that drain oil back to the pan are plugged. If the high volume pump is also higher pressure, there will be a slight increase in flow to the top.

 

It will not wear out distributor gears. The load on the gear is directly related to the resistance to flow. Oil pressure is the measure of resistance to flow. The Ford 427 FE "side oiler" used a pump with relief valve set at 125 psi and it used a standard distributor gear. Distributor gear failures are usually caused by a worn gear on a new cam gear and/or worn bearings allowing misalignment.

 

It will not cause foaming of the oil. With any oil pump, the excess oil not needed by the engine is recirculated within the pump. Any additional foaming is usually created by revving the engine higher. The oil thrown from the rod bearings is going faster and causes the foaming. This is why high performance engines use a windage tray.

 

It will not cause spark scatter. Because of the pump pressure there is a load on the distributor gear. The number of teeth on the oil pump gears determine the number of impulses per revolution of the pump. In a SB Chevy there are seven teeth on each gear giving 14 impulses per revolution. At 6000 RPM the oil pump is turning 3000 RPM or 50 revolutions per second. To have an effect on the distributor, these impulses would have to vibrate the distributor gear through an intermediate shaft that has loose connections at both ends. Spark scatter is usually caused by weak springs in the points or dust inside the distributor cap.

BTW

> The bottom of a Chevrolet distributor housing can be modified to spray pressurized oil onto the distributor drive gear. The extra lubrication will reduce distributor gear and camshaft gear wear. This is especially important when the gear is used to drive non-standard accessories, such as a high volume oil pump, or a magneto that puts additional loads on it and the cam. <P>When the distributor is installed, the bands at the bottom of the housing are designed to complete the internal right side lifter galley on all small and big block Chevrolet V-8’s and 90° V-6 engines. If you hand file a small vertical groove .030" wide x .030"( <B>thats the diam. that crane recommends Ive always used the larger groove with no problems</B>)deep on the bottom band (above the gear), pressurized oil running between the two bands will be directed downward onto both the gear and the cam.<P>This procedure is recommended for all Chevrolet engines no matter what material gear (cast or bronze) or what type of camshaft (cast or steel) you are using.<P> <P> <B> keep in mind the groove MUST be lined up with the cam gear when the distrib. is installed

as a general rule youll want to run the thinnest weight oil that will maintain about 20 lbs of oil pressure in a hot (200f)engine at idle, remember oil flow over the bearings COOLS by ABSORBING HEAT and carrying it into the oil pan, oil cooler or letting the cooler block surfaces absorb the heat for the cooling system to remove, to cool the bearings and lifter contact points ETC. the greater the voluum of oil flowing over the bearings the more heat can be carried away and the more constant the surface temp. can be. and be fore someone jumps in with that [color:"red"] old myth that oil flowing over the surfaces to fast will fail to pick up the heat from the bearings [/color] let me point out this chart

 

 

http://www.diabolicalperformance.com/clearances.html

heres other info,

http://www.babcox.com/editorial/ar/ar10180.htm

 

http://www.thirskauto.net/BearingPics.html

 

http://www.waynesgarage.com/docs/oil.htm

 

http://www.jimcookperformance.com/TechNotes/TN%2023.html

 

 

here this will help

 

 

http://www.babcox.com/editorial/us/uhs89734.htm

 

http://www.thirskauto.net/BearingPics.html

 

 

http://www.babcox.com/editorial/ar/ar20128.htm

 

http://www.babcox.com/editorial/cm/cm99828.htm

 

http://www.thirskauto.net/Engine_Thrust_Bearings.html

 

http://www.aera.org/tech/tb1465r.htm

 

http://www.dragnbreath.com/Clevite/TN%2016.html

 

http://www.dragnbreath.com/Clevite/TN%2022.html

 

http://www.dragnbreath.com/Clevite/TN%2028cambrgs.html

 

http://www.dragnbreath.com/Clevite/TN%2028cambrgs.html

 

 

 

http://www.jimcookperformance.com/TechNotes/TN%2028cambrgs.html

 

http://www.babcox.com/editorial/ar/ar10180.htm

 

http://www.babcox.com/editorial/us/uhs69720.htm

 

 

 

 

 

http://www.cryoeng.com/images/EngineDurabilitySecrets.htm

 

http://www.melling.com/engoil.html

 

http://members.aol.com/carleyware/library/engine2t.htm

[2Forty]

I have been using Mobil 1 in all my cars for years. I change the filter every five thousand miles then do a complete oil change every third filter change. Have never had any type of engine related failure. The synthetic formula doesn't break down like traditional oil and lasts a lot longer. You can change it every 3000 or 5000 if you like but I think its a waste of money.

[Guest greimann]

Due respect to the other comments, I feel compelled to correct a few things. Being a service engineer for Castrol Industrial, I have some background in this.

 

Synthetic oil is not "slipperier" than conventional oil. It may have some polar attraction that helps it cling to a surface when the engine is stopped, but it's two main benefits are resistance to oxidation (degradation) due to extreme heat and a high viscosity index without the use of viscosity improvers such as polymers, which are prone to shearing out under pressure. These features help synthetics maintain hydrodynamic separation of the moving surfaces to combat wear.

 

Detergent oils were developed along with the introduction of oil filters. Early motors did not have oil filters. The contaminates were intended to drop out in the oil pan, and very frequent oil changes were prescribed. Detergent oils hold contaminates in suspension until they can be removed by the oil filter, and thus extending drain intervals. Your lawn mower does not use deterget oils for this reason.

 

The most important consideration when considering the grade of oil to use is the temperature environment in which they are operating. In Frostbite Falls Minn. you will need a 0w to 5W oil in the winter to make sure the oil flows when cold. In So-Cal a 20W is fine because the temperature never gets below 40 deg F. in the winter. The other end of the grade desigination is for operating temperature that is also dependent on the condition of the motor as Grumpy stated. A sloppy motor in Arizona will need a 50 grade for sure. A tight motor can live with a 30 grade. 5W-30 is usually specified in new cars because the oil is light enough to increse fuel mileage by reducing pumping losses, but will still protect the motor because the motor is still tight.

 

Another note is 10W-40 conventional oil is pretty much expressly NOT recommended by any vehicle manufacturer. The reason is that to create a 10W-40 viscosity in convention oil, you have to add a LOT of polymer that displaces the other antiwear additives which compromises the lubrication qualities of the oil. Synthetic oil in 10W-40 does not have this limitiation because it does not use polymers to obtain the viscosity index.

[Oltmann]

My favorites are Mobil 1 Supersyn 0w-40 and Castrol Syntec 0w-30. The Mobil is a light 40 weight and the Syntec is a heavy 30 weight so these can be used almost interchangeably.

If you get the Syntec make sure it says "Made in Germany" as there are two different kinds. You can get these two from Autozone for about $5 a qt. In fact, Autozone may be the only place to find these.

 

If you want to save some money, occasionally Walmart carries Mobil 1 5qt jugs for $15-20. They don't sell the 0w-40 this way, but a 30 weight is good too. I would stay away from the other Syntec grades though.

[Synlubes]

I had to put my plug in here !

 

http://www.amsoil.com/products/cars/index.htm

[Guest Anonymous]

DELETE

[Sumo]

Has anyone here have info or used the Wal Mart house brand synthetic? They're only $2 a bottle!

[Guest the_dj]

Has anyone here have info or used the Wal Mart house brand synthetic? They're only $2 a bottle!

 

Is it full synthetic or blend? Sounds like a deal I too want to know what's up with it?

[Synlubes]

Folks,

 

You Get What You Pay For !

There`s high quality lubes and there`s less than high quality lubes.

Cheap "whatever" is cheap "whatever" ! ! !

[Guest soulfly454]

hey dcarrow beofr u go off telling people to buy amsoil i have seen with my own eyes some amsoil in a subuaru wagon thing that was maybe all of 4-5 years old well the story is the lady who oened it brought it in our auto tech shop and while we were all checking the fluids i checked the oil which immidatly look strange to me it was completely black and goopy so i got my teacher not being an expert my self when we drained the oil it was nastyer the crap in my dads 56 chevy which was sitting sine befor i was born so we askrd her how long it was in there this was her response (um im not really sure about a 2 years but ive only went 45,000 miles and the AMSOIL guy told me that the oil will last over 400,000 miles alright yeah thats such a crock and i felt sorry cuz she has a subaru which is fairly new that smokes like a crack head on pay day

[Phantom]

Wow - wish I hadn't missed this string of posts. I already knew the stuff on the synthetic vs standard oils but was unsure of the grade to use. Anyway, I just came out of AutoZone a short while ago after buying 5 quarts of 15W-50 Mobil 1. They were out of the 5W-30 and 10W-40 so my other choice was a 0W-30 or 40. Since I'm new to the LS1 and this is Texas and it is summer I opted for the 15W-50.

One comment, however. One thing no filter will do is remove the acids that are byproducts of combustion from the oil. They will continually build up over time and willl start to corrode the internals of the engine. - unless you regularly change out the oil whcih takes the acid build-up out with it. That is why, even with the Mobil 1, I'll be changing my oil every 5,000 miles or 6 months.