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Originally Posted by benjen
(Post 3853797)
Not trying to be a wise guy here, but there are other issues causing the failures. No oil is going to make something wrong all of a sudden right. With that said I'm not a chemist and don't know the why's. But, I do know first of all that gear lube viscosity isn't measured the same as motor oil. A 75 viscosity is not nearly as heavy as you think. I believe it is more like a straight 30 maybe 40 weight motor oil. Second, and more to the point is as mentioned above the add packs. What is important is the oil's shear strength, it's ability to stick to the gears. A good synthetic 75/90 or 75 whatever according to who you use is fine. I do not believe the heavier oil is going to make a difference in its ability to bond on the gear.
In class 8 semi trucks, most run 50WT engine oil, or 80W90 in the transmissions, and 80w90 in the rear diff's. Parts go a million miles plus sometimes. Cant say theres no load on those gears hauling 80k + lbs up mountains. |
i was suprised when it was time to change the gear lube in my ford f250 4wd,it called for 85w140 in the rear axle,and the gears are large for a pick up truck.
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Originally Posted by mike tkach
(Post 3853853)
i was suprised when it was time to change the gear lube in my ford f250 4wd,it called for 85w140 in the rear axle,and the gears are large for a pick up truck.
My trans temp in my semi on a hot day fully loaded runs about 160-180*. I think if the gearcase temps start getting in the 220+ range the 140W oil works better. I wonder if I should add a temp gauge on my dually rear end and see how hot it gets towing the boat. That would be cool, and a good way to determine what oil to run in it. Be nice to add one for the drives on the boat too! Of course synthetics play a role too! |
Originally Posted by MILD THUNDER
(Post 3853860)
I think its a temp thing. If the operating temp exceeds a certain number, the thicker oil comes into play. I don't think its as much as a strength thing as it is temps. Im sure ford had a valid reason to change the spec on that diff, as it used to be 80w90 I believe in the Dana 80, if that's what you have in yours?
My trans temp in my semi on a hot day fully loaded runs about 160-180*. I think if the gearcase temps start getting in the 220+ range the 140W oil works better. I wonder if I should add a temp gauge on my dually rear end and see how hot it gets towing the boat. That would be cool, and a good way to determine what oil to run in it. Be nice to add one for the drives on the boat too! Of course synthetics play a role too! And if zero or five weights are so good in a nascar engine,who's going to be the first one to use it in his boat engine?? not being sarcastic...just curious,as im always willing to learn something |
Thicker oil actually increases temperature.
Bravo Shop 75-90w oil will protect up to 400 deg. Talk to the folks that have used it and have seen unbelievable results not only in gear life but bearing life as well, they still look like new after being used for a season. We have been testing a 50-60w also in outdrives with the same results as our 75w-90. We have temp senders for outdrives and I have adapter them to my dually just for the same reason Mild Thunder stated above and I now run Bravo Shop 50-60w oil in rear axle and in the manual transmission of my 04 Chevy. |
No doubt.
Originally Posted by benjen
(Post 3853797)
Not trying to be a wise guy here, but there are other issues causing the failures.
Thanks for all the help guys. Keep it coming. |
Now, this is a cool debate:party-smiley-004: typically oil with wide viscosity ranges are used where tolerances change alot. NASCAR, and other racing organizations typically use low weight oil because it flows easier and creates less resistance to pump (free HP). Most "real" race engines are not loaded fully until brought up to operating temp to ensure the clearances are at a predictable size. A good oil, will hold the film size (based on the viscosity) at the temps they are designed for.
In my opinion, drive tolerances are wide enough to support the 140W (in multi-viscosity design only) number. But not enough to make up for being compromised due to excessive load. |
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Do a Google search on REM polishing. I know some people in the race car world are having very positive results, with transmission and rearend gears.
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