4.77 diff oil question
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Joined: May 2018
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From: Munich - Germany
I think that Honda maybe specd a SAE 90 single grade because this oil does not contain Viscosity Index Imoprovers like a (Example) multigrade 75w-90 gear oil or or a 5w-40 engine oil.
These Viscosity Index Improvers (Polymers) are pron to mechanically shear down in use, wich results that the oil becomes thinner over time in use.
Best example are motorcycles wich, thanks to the gearbox, thins a xxW-40 into a xxW-30 in no time.
If you look at pictures of a torsen differential you see that these contains a lot of gears wich makes it the perfect "Oil grinder".
While modern synthetic SAE 75w-90 or SAE 75w-110 are most likely superior to a older fashioned non-synthetic single grade SAE90, i would neverthelss be cautios and change it according to hondas service shedule or more often.
These Viscosity Index Improvers (Polymers) are pron to mechanically shear down in use, wich results that the oil becomes thinner over time in use.
Best example are motorcycles wich, thanks to the gearbox, thins a xxW-40 into a xxW-30 in no time.
If you look at pictures of a torsen differential you see that these contains a lot of gears wich makes it the perfect "Oil grinder".
While modern synthetic SAE 75w-90 or SAE 75w-110 are most likely superior to a older fashioned non-synthetic single grade SAE90, i would neverthelss be cautios and change it according to hondas service shedule or more often.
Joined: Aug 2013
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From: Sweden
Older thread but with some very good information.
https://www.s2ki.com/forums/s2000-un...-more-1203610/
https://www.s2ki.com/forums/s2000-un...-more-1203610/
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Joined: Oct 2010
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Sorry, I cannot tell you that. I've never ran 90 in my current car and I don't pay attention to my MPG, plus I've been running 80w250 for years now.
I can say that going from 75w140 to 80w250 doesn't seem to be a huge impact. I still have roughly half a tank of gas by the time I arrive at the track when leaving my house with a full tank.
If you are that concerned with MPG then I would advice against 4.77s. You can use the money you save by not doing to buy more gas
I can say that going from 75w140 to 80w250 doesn't seem to be a huge impact. I still have roughly half a tank of gas by the time I arrive at the track when leaving my house with a full tank.
If you are that concerned with MPG then I would advice against 4.77s. You can use the money you save by not doing to buy more gas
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Joined: Oct 2010
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The temp of my rear end didn't change(as far as I can remember, I did this back in 2010) going from 75/90 to 75/140. But the heat that our rear end creates is much greater than all the other cars I've had, I think because of how little gear lube it holds.
I know a lot of race cars that run in different series that have oil coolers for the third member to dissipate the heat so the gear lube doesn't thin out of a safe operating range. 477 gears will run hotter than 410 gears just driving down the road at speed. If you have been on here for years like some of us, you would have read about 100's of rear ends that have bit the dust. The thicker the gear lube the more cushion it gives to the shock of gear shifts or getting on and off the throttle.
As for gas mileage, I doubt you will find any measurable difference from the lube.
Food for thought, the rear end my 22,600 lbs motorhome towing a 4,000 lbs toad runs cooler than my S. But the rear end in my m/h holds around 3.5 to 4 gallons of gear lube. What does the S hold 1.5 or 1.6 pints.
Rod
I know a lot of race cars that run in different series that have oil coolers for the third member to dissipate the heat so the gear lube doesn't thin out of a safe operating range. 477 gears will run hotter than 410 gears just driving down the road at speed. If you have been on here for years like some of us, you would have read about 100's of rear ends that have bit the dust. The thicker the gear lube the more cushion it gives to the shock of gear shifts or getting on and off the throttle.
As for gas mileage, I doubt you will find any measurable difference from the lube.
Food for thought, the rear end my 22,600 lbs motorhome towing a 4,000 lbs toad runs cooler than my S. But the rear end in my m/h holds around 3.5 to 4 gallons of gear lube. What does the S hold 1.5 or 1.6 pints.
Rod
Could the winter temps lead to more drag in the cold? In winter I have the worst mpg. Or will that be due to other cirxumstances? In summer I make longer trips.
in winter my mpg drops to 15-17
Last edited by simons; May 27, 2025 at 11:13 PM.
Joined: Jul 2014
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From: Chesterfield VA
1. How does one determine differential temperature and is there a reference to what it should be?
2. 110 grade, as many have mentioned, matches the "old" 90 grade very well.
3. As for thicker or thinner oil the Engineering Explained video released in the past few days has some good information. Watched it last night. Need to watch it again now that I'm more fully awake. It's concerned with motor oil but the principles should be the same.
-- Chuck
2. 110 grade, as many have mentioned, matches the "old" 90 grade very well.
3. As for thicker or thinner oil the Engineering Explained video released in the past few days has some good information. Watched it last night. Need to watch it again now that I'm more fully awake. It's concerned with motor oil but the principles should be the same.
-- Chuck
Joined: Sep 2014
Posts: 11,359
Likes: 1,795
1. How does one determine differential temperature and is there a reference to what it should be?
2. 110 grade, as many have mentioned, matches the "old" 90 grade very well.
3. As for thicker or thinner oil the Engineering Explained video released in the past few days has some good information. Watched it last night. Need to watch it again now that I'm more fully awake. It's concerned with motor oil but the principles should be the same.
https://www.youtube.com/watch?v=i0VoEhW2I-E
-- Chuck
2. 110 grade, as many have mentioned, matches the "old" 90 grade very well.
3. As for thicker or thinner oil the Engineering Explained video released in the past few days has some good information. Watched it last night. Need to watch it again now that I'm more fully awake. It's concerned with motor oil but the principles should be the same.
https://www.youtube.com/watch?v=i0VoEhW2I-E
-- Chuck
Thanks!
Joined: Jun 2003
Posts: 575
Likes: 173
While modern synthetic SAE 75w-90 or SAE 75w-110 are most likely superior to a older fashioned non-synthetic single grade SAE90, i would neverthelss be cautios and change it according to hondas service shedule or more often.
I used Motul 75w140 which they claim " 0% shear loss: Unshearable oil film in extreme conditions."
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