Mobil1 in 915 bad??

[dbrisson]

I know I should have waited and ordered swepco but I had changed the trans fluid since I bought the car and started to get a little grind during 1st to second under load shifts.

I drained the fluid and put in mobil 1 and it started shifting great smooth as silk. After a days drive I started getting shuddering when starting from a turn. Jacked up the car and spun one wheel and heard the diff howl and growl.

Luckily I have a drill pump so changing fluid is quick, I drained it and put in dino 90wt with limited slip additive and after a few drives the howl is gone and the shuddering is going away.

I guess I should order swepco now and do it a third time.. any thoughts???

[rouxroux]

I did not know there was a Mobil 1 with a high enough viscosity to be used as tranny oil!

[the]

I'm gonna assume he used Mobil 1 gear oil.

[rcecale]

From what I've read here on this BBS, you really want to stay away from synthetics inside your 915. The synchros rely upon a little bit of friction in order to function properly. the synthetic stuff is just too slick to work inside a 915.

The general consensus here is to go dino, or stay at home.

Randy

[dbrisson]

Mobil1 makes a 75-90w gl5 lubricant, but it was definitely a new feeling and the diff was howling. It did shift smoother. Now with the dino the noise is completely gone and hopefully the grabbing completely goes away.

On a side note from the look, smell, and senses swepco looks just like the same dino blue gl lubricant that mercruiser uses in its high performance outdrive transmissions. I have tone of the stuff for my bravo iii sterndrive.

I wonder if there is a comparison? Minus the emulsifiers in case small amounts of moisture enter an outdrive the environment is as harsh or harsher than that of a transmission / differential. There are shifters, synchros and ring an pinions spinning in a high heat high load environment. Not sure if I want to try a direct substitute, maybe a mix?