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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH75W-90 vs 80W-90
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Check labels
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1
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Suggestion
btw I did some research on this in the past it's gl4 and redline recommended the 3,1 combo.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
Be sure to use GL4 fluid designed for syncromesh transmissions.
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11 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T130754Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Is it a sin to put 80W-90 in the transmission when the manual calls for 75W-90?
Planning on changing out the fluid. Furthermore, does it matter to use Mobil 1 Full Synthetic instead of Valvoline Semi Synthetic? Thank you.
The thicker 80w90 may be more difficult to shift when the transmission is cold. Be sure to use GL4 fluid designed for syncromesh transmissions. GL5 gear oil is good for the ring and pinion but the additional anti wear additives may prevent the syncronizers from working properly. Also the additional sulfur based additives in GL5 may corrode brass parts.
Since the factory recomends a synthetic I would not change to a semi synthetic. The cost difference is onlty $4 per quart so the total difference is $15. Its not worth it to me just to save that little amount. As far as using a 80W-90 will be fine as long as it meets the correct GL specifications. As said before it might make cold weather shifting a bit more notchy, but not that big of a difference.
Check your owner's manual for the GL spec.
The owner's manual for my '90 964 C2 (with synchromesh) specifies GL5, not GL4.
If your owner's manual specifies GL5 rather than GL4, you might want to do a little more research before deciding.
so what does the 996 transaxle take? I am going to change mine and forgot what I used and or what would be best swepco mt90, 75w90 or mobile 1 75w90? gl4 or gl5? Thanks.
