Delvac vs Mobil 1 gear oil for a 1st Gen W59 manual.

roving1

Well-known member
Any one use commercial Delvac 75w-90 gear oil for a transmission vs Mobil 1 75w-90? The FSM says I can use gl 4 or 5. Delvac is gl 5 and Mobile one is gl 4.

I can get a gallon of Delvac for $30 vs $60 for 4 liters of Mobil 1.

Be nice to not muck up the shifting but it would also be nice to save $30.
 

roving1

Well-known member
OK sort of answered my own question on that. GL5 is not swell for syncros despite being listed in the FSM. So I will just have to track down some Mobile 1 or Redline MT 90 somewhere everybody only seems to have 1 quart lying around.
 

DaveInDenver

Middle Income Semi-Redneck
I'd only put in GL4 in a W5x personally. I like MT90 but if the Mobil1 is GL4 that's what I'd use.

FWIW, I'm uncertain about how bad GL5 really is to yellow metals in transmissions made in the past decade or so. My manual on an RA60 calls for GL4 or GL5 so I have to assume Toyota knew the risk. So it may not be anymore.

Or perhaps they don't expect the rest of the transmission to last long enough to make it problem if the synchros wear out quickly.

Or my theory is that no one at Aisin or Toyota knows jack about building stick shift anymore and doesn't realize it matters.

I am, however, sold on MT90. It worked absolutely great in my W56 and so I've always used it in my RA60.
 
Last edited:

roving1

Well-known member

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