Engine/Transmission (1998.5 - 2002) Rear differential fluid

[Texas Diesel]

API MT-1 designates oils for heavy-duty truck and bus manual transmissions. Its focus is on improved high-temperature cleanliness and stability, oxidation and anti wear control, and compatibility with oil seals and copper alloys.



http://www.oilmedic.com/additives.html#GL



Interesting reading.

 

[Steve M]

I just bought some Valvoline SynPower full synthetic 75W-90 gear oil. It's GL-5, MT-1 rated. I keep reading about MT-1 having to do with compatability with oil seals among other things. With the luck I've had with oil seals, this can only be a good thing.

 

[C Schomer]

No seal problems with RP. I put new diff bearings in and the pinion seal looked so good, I reused it. Good thing, I didn't have a new one. It's holding fine. Craig

 

[Pit Bull]

Originally posted by Texas Diesel

Let me know what you find. I suspect that they will all uprate their products to MT-1, it will probably be in the store the day after I put the Mobil 1 in the truck

The 2001 service manual requires GL-5 and MIL-L-2105-C only.

Texas Diesel, I quit fighting it. My 2000 service manual does not spec. MT-1 for the lube either and I don't think you can buy a better lube than Mobil 1 75w90. So I bought some today and did my rear diff. If the seals leak I have a 100K mile extended warranty and DC can fix the seals

 

[Steve M]

I just drained my rear end, wiped the cover out real good and re installed the cover. The sealer says to let it cure 10-12 hours. I'll let it cure over night and then fill it in the morning.

If I had it done at the dealership they would seal it and fill it. Do ya'll let it cure before filling it or fill it right after putting the cover on? I don't know if it needs to cure empty or not. Maybe for kicks I'll put a little blob of sealer in a cup and pour some oil in with it and see if it prevents it from curing or disolves it.

 

[Texas Diesel]

I just put the sealer on, let it skin over for a few minutes and then install the cover. I add oil right away, never any leaks, the mechanic does it the same way.



Pit Bull, same here, Mobil 75W-90 and 8 ounces of OEM friction modifier, perhaps should have added only 6.

 

[Pit Bull]

I also added 8oz's, probably over kill with the Mobil 1. But I don't have any chatter

 

[Steve M]

I filled 'er up with Valvoline Synpower and decided to try it without the additive as the bottle states that it's good for limited slip differentials. With alittle over 100 miles this weekend there's been no chatter or scrubbing. But I did put the hammer down and left "two" black streaks on the pavement as I bulleted across an eight lane road. (I was going to Publix for some beer and subs!) No it didn't light 'em up and billow smoke but it will break 'em loose!