What Motor oil & Tranny fluid should i use???

[kawikid1425]

Hello i am looking to change all fluids in my 2003 lb7 dmax, i was wondering what to use and synthetic or not??? is amsoil good? cause i have a local dealer for amsoil. also can anyone tell me how much fluid the engin-tranny-t-case-and diffs are supposed to take. thanks alot

[DmaxMaverick]

Amsoil is one of the best, IMO. I use it. Synthetic is a good choice, for any of your lubes.

Engine: 10 qts.

Tranny: ~8 qts drain/fill. ~20 qts flush/fill.

Transfer case: ~2 qts.

Rear diff: ~3.8 qts.

Front diff: ~2 qts.

[kawikid1425]

thanks for your help! ok i dont understand the tranny fluid? i would like to change all of it, has 103.000 miles on it never changed. how do i flush it? i dont trust anyone else working on my truck! also i have heard to over fill the t-case w/ 3 qts. total/ overfill through sensor hole? all your help is much appreciated!

[DmaxMaverick]

The tranny pan has a drain plug. Normal servicing does not require pan removal. The internal filter (like traditional auto trannies) should only be replaced at overhaul, according to Allison. Unfortunately, like all autos, a drain/fill will not exchange all the fluid (less than 1/2). Much will remain in the torque converter, valve body, passages, and pistons. A flush is a dynamic exchange of fluid, allowing the tranny to pump out old fluid while you add new. Have a look at THIS THREAD (http://www.thedieselpageforums.com/tdpforum/showthread.php?t=33219), and THIS THREAD (http://www.thedieselpageforums.com/tdpforum/showthread.php?t=29507).

I've never heard of any benefit to a TC overfill, and I would not recommend it.

[kawikid1425]

ok those were helpful, if i understand correctly i need to take the drain plug out off the pan and let it drain. then take the spin on filter off? put a new one on? then put 8 qts. back in tranny and disconnect cooler line. start engine and run it through the gears. once i see the new fluid coming out shut the truck off and add 8 more qts. is this the right process if im changing over to amsoil torque drive? sorry tryin to take in alot off info!

[kawikid1425]

i decided to just change the filter, and drain the pan. then fill back up. instead of doing a complete flush. do i need to just put however much oil comes out back in?

[kawikid1425]

how may miles do you go on a amsoil engine oil? i dont trust driving my truck 50,000 miles without changing the oil!

[DmaxMaverick]

When doing the flush, the fill/run process will be done a couple times. Twice will exchange a little more than the total capacity, but doing it more will flush out more of the old fluid. But, you aren't doing this.

Replace the spin-on filter with new. Be sure to clean and reuse the magnet, located on the top of the filter element. It should come out with the filter, but sometimes they stick on the nipple. If you don't find the magnet, it's probably been tossed during a previous service. It can be had at an Allison distributor for a couple bucks, or $10-20 at the dealer. The dealer will usually have to order it, but the Allison distributor or service center should have them on hand. If you replace the fluid you drain, it should be close to the correct level. Check it once warmed up, anyway.

50K miles on engine oil? ONLY if doing regular oil analysis. Otherwise, it depends on the use of the truck. I change mine at 10-15K miles, but I don't make any short trips, and the engine gets fully warmed up and driven significant distance every time (I live in the sticks). I change it more often if towing a lot. Years ago, I did oil analysis on a couple changes. The results prompted me to use the change intervals I chose. The Duramax Diesel engine burns significantly cleaner than any Diesel engine prior, therefore, the service rules needed to change. 3K miles is much too soon with the oil I use, and driving I do. They may be able to go 50K under very strict conditions, but I wouldn't do it. "Can do" and "should do" are 2 very different things.

[kawikid1425]

thanxs for your help d-max, here is what i have decided to do, i am using castrol/alli transynd for the tranny, Amsoil sever duty 75-90 for the transfer case, rear and front differentials, and for the motor i havent decided. i dont want to run synthetic because of the loss in oil pressure. if you can tell me a syn. that doesnt make you lose oil press. i would run it. if not what do you feel the best dino oil is to run in my lb7? thanks dmaxmaverick!

[Hillbilly Jim]

I have never noticed any loss of oil pressure when switching to a synthetic oil, but then every thing I own except chain saws is lubed by one synthetic or the other since I purchased them. Maybe I dont have any thing to compare to.

[Mark Rinker]

What I would do, if this were my truck:

Mobil Delvac synthetic (silver jug) w/10-15K change intervals, max depending on use and conditions;
Sythetic gear lube in front and rear diffs, 50K-70K intervals depending on use and conditions;
Synthetic ATF in the transfer case; ~50K-70K depending on use and conditions;
Conventional ATF (Dextron III) in Allison, start with a complete flush, then '7qt drain and fills' with new Delco spin-on filter each time at 25K-30K intervals, depending on use and conditions;
Don't forget chassis lube!My .02 worth. Good luck...

[kawikid1425]

THNAKS GUYS, Mark i see you say you plow with your truck? i just installed a new Boss 7 6'' on mine. any advice you can give me on that? temp. changes, etc... let me know please. also i thought that the Mobil oil didnt meet the reccomendations for a dmax engine?

[DmaxMaverick]

First things first...DO NOT USE GEAR LUBE IN THE TRANSFER CASE!!!!!! Use the same fluid you use in the tranny, Dexron III. Gear lube will kill it, in a hurry. It is designed to use ONLY Dexron III. The TC has an oil pump, and there's a huge difference between 10 weight tranny fluid vs. 90 weight gear lube.

Oil pressure is overrated, in most cases. I haven't experienced any significant pressure decrease with synthetics, but it is noticeable under some circumstances. Synthetic multi-grades (of a comparable dino weight) flow MUCH easier at lower temps. I can see how this could give an impression of lower oil pressure. Fact is, the dino oil pressure is too high. Synthetic is able to maintain a more consistent viscosity over a larger temperature range. Bottom line, IMO is, oil pressure is NO reason to disqualify the use of synthetic oil. More on this discussion, if you wish.

Transynd is good stuff. Overpriced and no better than the Amsoil, but good. The TES-295 rating of this fluid only applies to medium/heavy duty commercial applications, according to Allison. Also, Transynd is quite a bit more costly than Amsoil TorqueDrive. I've been using the Amsoil fluid (both Universal, early on, then TorqueDrive when it was released) for over 100K of very heavy, hot, mountainous and abusive towing, and it's held its own. Nothing wrong with Transynd, but I think it's way overpriced.

[kawikid1425]

ok maverick im going to take your advice and state what im going to do. tell me if i have anything wrong or if you would do it differently.

Engine- Amsoil 15/40 synthetic- 10 qts.
Tranny- Transynd- put back in what i drain out w/ new filter
T-Case- Transynd or Torque drive- 2 qts.
Rear Differential- Amsoil 75/90 severe duty gear lube- 3.8 qts.
Front differential- Amsoil 75/90 severe duty gear lube- 2.0 qts.

Also new ac/delco fuel filter

Will all of this be fine? Thanks for all of your good advice just want to make sure im on the same page that you are! This truck is my first diesel and i love it and want to take care of it. im sure you can relate to that. there is so many mixed opinions on this matter its crazy. so at some point you just have to find someone that you feels advice is good and go with it. because you could read the rest off your life whether to run dino oils or synthetics! thanks for your help maverick.

[Mark Rinker]

My apologies for the unclear posting above, grouping diffs and transfer case in the same bullet point, without pointing out the difference in fluid type. I have corrected that post...two different bullet points...

[Mark Rinker]

THNAKS GUYS, Mark i see you say you plow with your truck? i just installed a new Boss 7 6'' on mine. any advice you can give me on that? temp. changes, etc... let me know please. also i thought that the Mobil oil didnt meet the reccomendations for a dmax engine?

I just posted my thoughts yesterday on plowing with the Allison 1000 here: http://www.thedieselpageforums.com/tdpforum/showthread.php?t=33490

[DmaxMaverick]

ok maverick im going to take your advice and state what im going to do. tell me if i have anything wrong or if you would do it differently.

Engine- Amsoil 15/40 synthetic- 10 qts.
Tranny- Transynd- put back in what i drain out w/ new filter
T-Case- Transynd or Torque drive- 2 qts.
Rear Differential- Amsoil 75/90 severe duty gear lube- 3.8 qts.
Front differential- Amsoil 75/90 severe duty gear lube- 2.0 qts.

Also new ac/delco fuel filter

Will all of this be fine? Thanks for all of your good advice just want to make sure im on the same page that you are! This truck is my first diesel and i love it and want to take care of it. im sure you can relate to that. there is so many mixed opinions on this matter its crazy. so at some point you just have to find someone that you feels advice is good and go with it. because you could read the rest off your life whether to run dino oils or synthetics! thanks for your help maverick.

Looks good. Don't forget the chassis lube (11 points at the front suspension and steering), air filter, fuel filter, and of course, check other fluids as well. Inspect the accessory drive belt, too. Any serious cracks or glazing should prompt replacement, depending on miles/time. Also check idlers and tensioner pulleys at the same time. The should turn easily with minimal noise, and no lateral play. If you have a plastic idler pulley (likely), make sure it is in good condition with no nicks in it, and the grooves should be smooth and straight.

As far as your ATF choice goes, it's your choice. However, I suggest using the same fluid for tranny and transfer case, whichever you choose. No reason to complicate the matter, and having only one fluid cuts down on inventory. Transynd is fine in the TC, and isn't much more $ for only 2 qts.

Also.....If you are doing a tranny drain/fill, you can't count fully on a synthetic advantage. You will be mixing synthetic with dino, and the dino will always be dino.

[kawikid1425]

ok, but i thought the tranny had transynd in it from the factory????? thats why im putting it in! i dont want to mix 2 different oils. whatever is in my trans. i was going to put back in since im not doing a complete flush!

[DmaxMaverick]

The factory fill is dino Dexron III. Just off-the-self stuff.

[kawikid1425]

will it hurt mixing the transynd with that stuff? didnt want to flush it! or should i just fill it back w/ the dexron III

[Mark Rinker]

will it hurt mixing the transynd with that stuff? didnt want to flush it! or should i just fill it back w/ the dexron III

If you truly have over 100K on the original tranny fluid, I'd do a full flush and get every bit of that worn out fluid out of there, starting with fresh and new for your next program...even if its bright pink and looks good, its worn out at those miles. I'm guessing its more clearish than pink at this point. Q: Would you dump a half gallon of fresh milk on a half gallon of curdled - putting it back in the fridge for consumption? :eek:

As for my suggestion for synthetic in the transfer case...I am sure most here would agree that the transfer case and diffs are the easiest to overlook and go past normal/wise change intervals. Having synthetic in them (ATF in transfer, Gear Oil in diffs) - ensures a higher level of protection.

Using conventional in the Allison makes it economical to do frequent changes - your cheapest insurance for a long service life.

I think its smart that you are thinking through this program, and not peice-mealing your approach! Good luck with your truck.

[kawikid1425]

Thanks for your response Mark R. I love my truck and want to do this right! im not that experienced with the trannys. that is why im scared to do the flush. my truck has 103,000 miles. the flush sounds complicated! BUT i would love to have all fresh syn. fluid in there. do you feel i really need to do a complete flush? or just change the filter and fill back up? i will do the flush but it just sounds risky to me.

[Mark Rinker]

Then do two rapid drain and fill intervals, like 500 miles apart...then do another in 5K miles...and a fourth at 10K. Conventional ATF as described above will do fine - if you really want synthetic, switch over at 10K or the fourth change.

~7 quarts drains out, and the total capacity is 20 quarts, so you should be in pretty good shape 15K miles from now, and resume a more normal interval based on your use. Towing and heat are the factors that shorten trans fluid life.

I'll go out on a limb here, but after the first spin-on filter replacement, I think you could safely leave that one on, until your fourth change. Use a good OEM replacement from Allison or GM, and make sure to transfer the magnet from filter to filter...there are some cheap internet knockoffs out there.

How does the fluid look today? Pink? Brown? Stinky or fresh tranny fluid smell? If the truck was a daily driver, it should be okay...if it towed with any regularity in hot weather, its worn out...

[kawikid1425]

looks kinda red, so what you are saying is, to drain the trans. oil. then fill back up with whatever oil i decide to run in it. then drive it awhile. drain again and again and again. so basically after awhile it will be full of the new fluid im trying to convert it over to?

[Dirtbikindad393]

ok, but i thought the tranny had transynd in it from the factory????? thats why im putting it in! i dont want to mix 2 different oils. whatever is in my trans. i was going to put back in since im not doing a complete flush!

Transynd doesn't come factory in the trans. It will not hurt mixing trans fluids, synthetics like Amsoil are compatable with other fluids. This is why earlier posts say to fill and drop and fill and drop on short intervals to get it almost completely changed over to synthetic after maybe not ever being changed.

[Mark Rinker]

looks kinda red, so what you are saying is, to drain the trans. oil. then fill back up with whatever oil i decide to run in it. then drive it awhile. drain again and again and again. so basically after awhile it will be full of the new fluid im trying to convert it over to?

Exactly. Drain and refill method will drop about 7-8quarts each time. Eventually your fluid will be 90% new over the next 20-30K miles...

[jjcsnlynn]

What I would do, if this were my truck:

Mobil Delvac synthetic (silver jug) w/10-15K change intervals, max depending on use and conditions;
Sythetic gear lube in front and rear diffs, 50K-70K intervals depending on use and conditions;
Synthetic ATF in the transfer case; ~50K-70K depending on use and conditions;
Conventional ATF (Dextron III) in Allison, start with a complete flush, then '7qt drain and fills' with new Delco spin-on filter each time at 25K-30K intervals, depending on use and conditions;
Don't forget chassis lube!My .02 worth. Good luck...

I've seen several posts here to use Dextron III in the Allison Trans, but the autoparts stores say to use Dextron VI (6). What's the difference and what should I use on an 04 2500HD?

[Shed]

About the only thing I am well versed in on the site!

I started using Amsoil, and then became a dealer.

I did exactly as Mark stated to do and it has been the best thing I did to my truck! As far as the tranny goes, follow Marks advice. I personally went a little farther, I drained, dropped the pan, replaced the internal filter, replaced pan with after market pan, replaced spin on filter, and now to a drain and refill and spin on filter every 20K. 12-15k if I'm towing hard. I use the Amsoil ATF, and Wix spin on filters.

I use the 15w-40 heavy duty diesel/marine oil. I also use the Amsoil EA oil filters. Amsoil will tell you 1 year 25k miles, and I trust this and have the oil analysis to back this up. I never hit 25k on my truck, and change it once a year and do an analysis. Amsoil also has a kit for that. When starting to use amsoil I used thier engine flush, but with a little twist. First get a new wix filter, take off the old filter and put the Wix on. Pour in the engine flush in the oil intake. Start truck and let it run for 20 minutes at IDLE. Do not rev or drive with engine flush in! Remove filter and oil (engine flush in it) and replace with EA oil filter and fresh Amsoil. I have NEVER seen any problems with oil pressure related to Amsoil or any other synthetic.

As for TC, use the universal ATF just like the tranny.

Use Severe gear 75w-90 in both Diffs. Amsoil sells a neat little pump that makes this alot easier, or you can rig one out of an old hand soap dispeneser
and some clear tubing.

And dont forget the Chassis lube!

You can go Amsoil.com and do a vehicle look up to get a list of all reccommended fluids.

Good luck! Merry Christmas! Shed

[JohnC]

This thread is 2 years old. The correct fluid for the Allison is Dexron VI
(6) or Castrol Transynd. The transfer case uses the same ATF as the transmission.