Accidentally had a shop put in 75w140 for the MT fluid...
 

As the title says, put a much thicker gear oil than most people use. My question is, is it worth buying a better thinner oil and swapping it.

Is there any ill effects that could hurt the tranny?
I've heard mixed things, but pennzoil 75w90 and eneos 75w90 seem to be some of the highest rated gear oils for the trans

Thanks ahead of time

I don't know. Is your transmission worth it? Why not put corn oil in the engine? oil is oil right? Leave it in there and find out.

Is your car a purpose built racecar that sees elevated temperatures constantly and eats transmissions as a consumable?

No?

You should probably go to a thinner oil, as I doubt your bearings and gears are happy with something that thick.

Edit: Also make sure its not a GL-5!!!!!

I'll second that ....... ;)


humfrz

I'll just add in again so it cannot possibly be missed.

Make sure that oil is not a GL5 or you'll be fighting a corrosion problem on top of a lubrication problem!

^^By far the most important point in this thread.^^

Thank you gents, I'll be swapping out the trans fluid tomorrow. Luckily it hasn't been more than day so no real damage has been done.

I would consider switching over to Motul Gear 300 75w90. We've had great success with this fluid in 100s of customer cars over the years. This fluid gives you very smooth engagement coupled with full synthetic protection. Our Project BRZ which is a track and street car as well as our Spec86 Cup wheel to wheel race car get this in both the transmission and rear differential.

We never suggest anything that we don't use in our own vehicles and haven't tested ourselves.

You can purchase (4) Liters for $85 shipped through us as well. http://store.azpparts.com/fluids/motul-gear-300-75w90/

-mike