SU Carb-wells have run dry, ATF is the answer but...

[Kanzen]

What density/grade of ATF would you recommend for SU Carb well refills?

I have had a search through the Hybridz.org Forums and had a read through some books I have, they all say ATF is the way to go, but none say what "type".

 

Was in the Auto shop the other day and shat bricks at the wide variety of ATF they had on shelves, please help me other brothers (and sisters) I asked the store attendants but they were shocked to hear I had the car let alone know what grade would be best.

 

Running '71 Roundtop SUs on a 280ZX T engine converted back to Carbs.

 

I figured this section, being Troubleshooting, would be the way to go, seeing how it didnt really seem to fit in any other subforum.

[johnc]

ATF (any auto trans fluid is fine) is used if the weather is cold or you're running a lighter flywheel. In most other cases a 20W oil works well.

[Tony D]

Most ATF is an SAE 10wt oil. This equates roughly to an ISO VG32

The 20Wt oil John C refers to roughly equates to an ISO VG68

 

If you are rural, and have tractor supply stores nearby, the AW-Hydraulic Fluids are similar specification viscosity wise to what ISO grades are available, hence an ISO VG32 oil (ATF) would be similar in consistency and properties to an AW 32 hydraulic Fluid.

 

Same for AW 68 / ISO VG68 / 20Wt. As I recall, 30Wt is either ISO100 or ISO VG150... quite a jump.

 

You are looking for hydraulic dampening, so the VG is relative---you can see the difference between 20Wt and ATF is an ISO differential between 68 and 32. Why do I mention this?

 

Because now knowing the ISO / AW relationship, you can find ISO VG46 oils out there that 'split the difference' and knowing the ISO number will allow you to experiment on your own with known ISO VG grades where you will know the viscosity differential and can somewhat predict the difference in response.

 

Some Compressor Oils like Sullair SRF 1/4000 are ISO 46, so that gives you another alternative. But finding a liter bottle of the various grades will allow you plenty of oil for a lifetime of experimentation. If you find oil of the same manufacturer, you can 'mix' grades to split the viscosity characteristics as well.

 

I would never have thought this possible, but I got an E-Mail from Mobil Technical Department for a special application we had and we indeed were told to simply mix AW68 and AW32 to 'get' and AW 46 for testing at a remote site!

 

I mean, we're talking hydraulic dampners in SU's here...so a little experimentation isn't going to have earth-shattering consequences if the viscosity isn't 'spot on'...

 

happy experimentation!

[Kanzen]

ATF (any auto trans fluid is fine) is used if the weather is cold or you're running a lighter flywheel. In most other cases a 20W oil works well.

Awesome man, I will keep this in mind when going to the Autoshop next. From what I've been lead to believe, the flywheel hasnt been modified/lightened, though I had plans of running something lighter when I start fiddling with the Transmission bladyblabla, weather where I am is quite hot even throughout the winter, I will have to take a word out of Tony D's books and experiment with the different ISO levels.

 

Bible of ATF and ISO/Consistency

Thank you for the indepth explaination of ATF and oils, it really has put a new light to the situation, knowing that I can't really go "wrong", has definately taken a weight off my shoulders. That's what Z's are all about I guess, experimentation, trial and (lots of) error haha.

 

Thank you both for your help, it is greatly appreciated.