What engine and Trans Fluids to use

[jjcsnlynn]

Just bought my first 'real' truck and I'm need to change all the fluids. I did a search here but very confused with all the recommendations.

Just two questions.

Engine: I use Rotella in my VW TDI and see some use it in the Duramax, but others only in a pinch. Can I use Rotella T or should I use something better?

Trans: I'm reading Dextron IV is the regular fluid, but if I want to go synthetic I need to do some mods. Is Dextron IV OK and what are the mods?

[rapidoxidationman]

Dinosaur oil is good in the D-Max, 15W40 if memory serves. check the owner's manual or find one online if it didn't come with the truck. Tdi's are particular about the exact oil you use (I had an '01 Jetta for some time). Duramax's, not so much. Just make sure it is rated as a diesel oil.

GM says to transition to synthetic ATF: Dexron VI (read: 6) is the stuff. 7-8 quarts will do a drain/fill. Don't forget to move the magnet donut from the old filter to the new one.

[Heartbeat Hauler]

While I agree totally with the Rotella 15w-40, I don't know that I would tout the Dex VI. I feel that Transynd would be a much better synthetic choice in the tranny (also for the xfer case). This is for the older trucks ('01-'07). But, starting with the newer ('08 & up) I'm not so sure. As far as the front and rear differentials, I would suggest a good synthetic, i.e. Mobil 1, Amsoil, etc. in the GM recommended gear-oil weight.

If you want to go to extended oil drain intervals, you can step up to synthetic oil in the crank case, i.e. Rotella 5w-40 or Amsoil 15w-40. But if you are gonna change oil every 5000 to 7500 miles, stick with the Rotella 15w-40 dino. It's cheap and most importantly, available everywhere. Many Oil analysis results show that Rotella 15w-40 dino can go as much as 10k miles before changing depending on use and evvironmental conditions.

[Kennedy]

In an effort to minimize the number and types of fluids on hand I have been using Mobil Delvac 1 in my Dmax trucks along with my Deere 455 garden Tractor, Deere 3720 CUT, Honda Generators, Honda Rincon ATV, Polaris Ranger, etc. I end up buying Rotella etc. on occasion for customer stuff.

For the trans I use Transynd on my own stuff and most customer stuff. Dex III for odds and ends.

I should note that I also have 20w50 petro racing oil for my 2002 extreme duty (competition) engine.

[More Power]

The early Dmax 4WD trucks came with dino lube in the front diff, but they should all be equipped with synthetic in both front & rear differentials. There was a service bulletin issued a few years ago suggesting the front diff lube in the early Dmax 4Wd trucks be switched to synthetic. It seems some front diffs in trucks used in very cold climates could suffer failure because the stiff petro lube wouldn't flow, which resulted in bearing failures.

Jim

[Kennedy]

The early Dmax 4WD trucks came with dino lube in the front diff, but they should all be equipped with synthetic in both front & rear differentials. There was a service bulletin issued a few years ago suggesting the front diff lube in the early Dmax 4Wd trucks be switched to synthetic. It seems some front diffs in trucks used in very cold climates could suffer failure because the stiff petro lube wouldn't flow, which resulted in bearing failures.

Jim

Also note that if you have the black vent plug you shoudl switch to the white OR at least upgrade the oring to a synthetic compatible unit. If not it will look like a rubber band left out in the weather. All rotten and fuzzy on the surface. Around 2003-2004 this change was made as I recall.

[Heartbeat Hauler]

The early Dmax 4WD trucks came with dino lube in the front diff, but they should all be equipped with synthetic in both front & rear differentials. There was a service bulletin issued a few years ago suggesting the front diff lube in the early Dmax 4Wd trucks be switched to synthetic. It seems some front diffs in trucks used in very cold climates could suffer failure because the stiff petro lube wouldn't flow, which resulted in bearing failures.

Jim

Also note that if you have the black vent plug you shoudl switch to the white OR at least upgrade the oring to a synthetic compatible unit. If not it will look like a rubber band left out in the weather. All rotten and fuzzy on the surface. Around 2003-2004 this change was made as I recall.

What "brand" synthetic diff oil and weight do you recommend. And, where do you get the "white" vent cap?

[More Power]

Clip from GM Bulletin No.: 03-04-19-001B, Date: September, 2004

Use Synthetic Axle Lubricant, P/N 12378261 or P/N 89021677 (Canadian P/N 10953455 or P/N 89021678). Each of these part numbers is the same axle lubricant, with differences in packaging only. Fill to a level between 6 and 9 mm (0.25 in to 0.375 in) below the bottom of the fill plug.

If the vent hose connector is black in color, it will need to be changed so that the 0-ring seal is compatible with the synthetic lubricant. Install vent connector, P/N 12479390. Follow the Front Drive Axle Vent Hose Connector Replacement procedure in the Service Manual.

Jim

[jjcsnlynn]

Thanks all. So far I've put in Rotella Dino Diesel oil for my first change. I want to do the trans next week, but I can't find any place that sells Transynd . All I can find is Dextron VI. Where do they sell Transynd?

I'll hit the rear and transfer box next week to.

BTW, What filters do you use? I went to GM and got RAPED on the AC Delco oil and trans filters...about $35 each!

[DmaxMaverick]

Transynd can be found at most Allison dealers/distributors, and some truck stops. It is the recommended fluid for many Allison equipped commercial Medium/Heavy duty trucks. Mobil-1 and Amsoil are also excellent synthetic ATF's. Amsoil also has a TES-295 rated fluid (TorqueDrive...same rating as Transynd), at a fraction of the Transynd price. I use it.

The spin-on tranny filter can be had for about 1/4 the dealer price, and most any Allison distributors. I use Wix or Amsoil engine oil filters, but most of them are at least "good". All but Fram, that is. Friends don't let friends use Fram.

The external transmission spin-on filter magnet is locate on TOP of the filter (as it is installed, and can't be seen from the outside. It rests over the in/out holes of the filter.

[Mark Rinker]

I am a huge fan of Mobil Delvac for one main reason - it stays in the engine, without losing volume, for my 10K change intervals.

In the same period, Rotella will routinely burn through at least 1qt, and under extreme hot towing conditions, as much as 3qts.

Not a chemical engineer, but it appears to me that one oil is up to the task, and the other oil is breaking down and vaporizing out of the engine.

[jjcsnlynn]

Thanks. I put in Rotella Dino Diesel oil for the first change. Next time, I'll go with synthetic and possibly a Wix filter.

I'm doing the trans next week and will try to find some Transynd, if not, I'll go with the Dextol 6.

[Kennedy]

We stock Transynd in 6 gallon cases. Also Baldwin fuel and oil filters and genuine Allison trans spin on filters.