syn shear strength ?

[nicholas]

hey guys
i was wondering , if you took Mobil 10w30 conventional and mobil syn 10-30 .
which one would have a better shear strength.
i use 10-30 in my transmission case, and was going to add 25% of syn oil to the mix.

but for some reason i think that syn oil has less shear resistance in a manual gear box ?

thanks

 

[TallPaul]

I would think synthetic is more sheer stable since it has a higher viscosity index and so needs less viscosity index improver (VII) polymer added. In fact, most Redline oils don't have any VII added. Why not run full synthetic transmission fluid, some of which will fall into the 10w30 motor oil viscosity range. Both Redline and Specialty Forumlations make manual transmission fluids. They are expensive, but since they stay in there a long time it seems to me to be worth it.

 

[jthorner]

To your question, synthetic oils in general have better sheer resistance than do conventional oils.

I agree with TallPaul. If your manual transmission calls for 10w30, the simple answer is to use Redline MTL. It will work wonderfully in your transmission. I switched my '72 Volvo (weekend fun car) over to MTL from conventional 10w30 and the shift quality is excellent.

Motor oils are not optimized for transmission service. MTL is a little more expensive than synthetic motor oil, but you only need a quart or two and it stays in for a long time.

Specialty Formulations' transmission lube is probably good stuff as well, though I haven't used it myself.

John

[ March 14, 2005, 11:40 AM: Message edited by: jthorner ]