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Triumph TR6 - Can I use 80W-90 gear oil in the transmission?

I looked at two stores for the SAE 90. All I found was some Exxon superflo 80W-90. It has an API designation of GL5. However, the manual states to put in GL4. Is the 80W-90 okay to use? Thanks.
D J Guess

A quote from the Redline site may answer your question:

"GEAR AND SYNCHRONIZER WEAR PROTECTION
Most manufacturers of manual transmissions and transaxles recommend an 80W or 90W GL-4 lubricant. GL-5 gears oils which are required in hypoid differentials are not used in most synchromesh transmissions
because the chemicals used to provide the extreme pressure protection can be corrosive to synchronizers, which are commonly made of brass or bronze. Typically, the use of a GL-5 lubricant in a synchromesh transmission will shorten the synchronizer life by one half. The extreme pressure requirements of spur gears and helical gears found in transmissions are not nearly as great as found in rear-wheel drive differentials. A GL-4 lubricant provides adequate protection for most manual transmissions, unless a unique design consideration requires the extra protection of a GL-5."

Roger H

Don
There is a past thread on GL-4 vs. GL-5.
Roger hit the nail on the head. Do not use GL-5.
Rick C
Rick Crawford

I did a search but failed to find it. Thanks for the information.
D J Guess

Don
My search key words where " GL-4 GL-5" (all years)and the top thread of the list was "Differential GL-5 OK" Date of thread is March 2002. You MUST!!!! read the entire thread. If you only read half you will be putting in GL-5 in your tranny. I was in the GL-5 camp then had to eat crow (or is it goose) by the end of the thread.
Rick C
Willing to eat humble pie in order to help others:)
Rick Crawford

Jim,
Don't let Rick anywhere near 'the goose'!!!
Doug Campbell

This thread was discussed between 27/04/2004 and 28/04/2004

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