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Using synthetic oil in your z?

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I'm now using Mobil1 0w30 full synthetic oil in my Z. Turbo/carb setup on a F54 block/crank/rods, turbo oil pump, ITM cast pistons, N42 head with solid cam and spray bar. I rebuilt the entire engine and did the 5k mile break in on 10w30 standard oil, changing the oil/filter every 1k miles after the first 500 mile initial oil/filter change. This is the first time I have run full synthetic oil in any of my Datsun engines. I actualy get 10lbs of oil pressure during a cold engine crank to start, then the pressure jumps right to 60lbs. After the engine warms up to 200f water temp, I get about 15lbs oil pressure at idle/1100rpm and 50lbs pressure at 3.5krpm @ 60mph.


I do use the napa gold filter with anti drain back valving, so this is my guess as to the good oil pressure during cold start ?


I cant believe how much better my engine idles and starts cold compaired to standard oil. The only issue I have noticed is that my engine does consume a little oil, mabe 1/4 quart per 3k miles.


I'm actualy seeing some better mpg too, roughly 3mpg's better than before, while using standard 10w30 oil.


I decided to change my oil in my 1998 Toyota Corrola to the Mobil1 0w30, and guess what?? I get an average of 34mpg, compaired to 30mpg using standard 10w30 oil.


I have read the stories about premature engine component failures on older engines running newer full synthetic oils, however I don't know the condition of their engines when changed from standard to synthetic oil..


I do realy notice a difference in my Z engine, it seems to rev easier, start easier, and idle smoother.


Does the 1/4qt oil consumption per 3k miles seem odd?? OR is this due to the synthetic oil being realy darn slippery stuff??

Edited by 280zex
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Consumption is fine... The film strength of the syn oil leads to it being more difficult to "strip" off cylinder walls with he rings. So some stays afterwards and is burned......you don't notice it unless you're really hammering it hard!

this was my thought, also that my motor is still fresh and the rings still need to seat fully.

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I use this with my Mobil 1 in both my turbo cars.  http://www.torcousa.com/torco_product/zep.html


I've read about ZDDP additives, and there are a couple mainstream oils that have high ZDDP levels that I know of: Valvoline VR-1 and Amsoil. I believe both are synthetic, but I'm not positive on the Amsoil.


I currently have Castrol GTX High Mileage which I believe is part synthetic. Getting about 16mpg with 10w-40 but switching to 10w-30 full synthetic VR-1 soon so hopefully I'll see some benefits.

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On the milage increase..If you have ever dropped a full synth into a wet clutch system you will see how much better the synth lubricates.  Your machine may be immobile until you put a conventional back in.


On the Zinc and Phos, ZDDP is the most important thing in your oils additive package.  Whatever oil you use you can find the ZDDP ppm online. There are a lot of good ones out there these days.  We primarily build Porsche track cars at our shop.  I ran mobile 1 for years but to remain the factory fill oil the zinc ppm has fallen, with manufacturers saying the zinc may harm the cats that by law they must extend the warranty on.   We now run a Motul full synth with a great ZDDP package and have yet to have a customer spin a bearing...knock on wood. :-)

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I use this stuff:




It’s a blend and it really works great on engines high in miles. I’ve used nothing but Castrol products for the last 25 years in all types of cars and it’s never let me down.


I would think a straight synthetic in an older engine like our L28 would cause leaks. All my motorcycle friends hate synthetics because the older casings (even with good seals) don’t hold the synthetics.

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Leaks with synthetics are traced to usually two things: the synthetics ability to "wick", due to low surface tension characteristics, or incompatibility with seals used in older engines. In some cases oil manufacturers would claim their product would stop leaks because the composition would "swell" seals. Such marginal effects are rare these days--the oil either works, or you find dissolved seals in your pan!


There are some synthetic glycols used as oils that have a TERRIBLE wicking propensity...the entire engine or gearbox will eventually get a sheen of oil on it regardless! (Techtrol Gold III is one...)


Engines that use machined fits need supplementary sealants designed for these types of service to seal effectively. But new sealants are hard to get old timers to use in old machinery... "I done it for 30 years with Permatex #2 and it don't leak with the old oil...so why shouldn't it seal with the new oil?" Generally it is traced to surface prep and sloppy preparation.


We went through this on our assy line in Asia. They wanted O-Rings added, higher bolt torques, etc... When two of us came from the US and did 60 machines, and then traced the machines in the field or three years...(with no leaks-12 months past warranty expiration) the assembly line there begrudgingly changed their choice of prep solvent and suddenly the leaks on their stuff stopped as well!


Compatibility and Proper Prep solves most leak issues. Having a good PCV System helps as well.


Some designs are more prone to leak than others, and you just have to adjust accordingly.


Outside of high-wicking oils, the problem with leaks is engine design and seals, not the oils themself.

Edited by Tony D
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