Synthetic Fluid Changeover

Longshot · April 13, 2009

I have an '07 GMT900 2500HD D/A. I picked it up used, and It has just under 20,000 miles. I'm going to put in all synthetic lubricants, and I wanted to get some input on my changeover process.

Engine Oil: Since the oil is not as clean as it should be, I was thinking I'd do a 'rinse' change first with a standard oil, just to flush out the system. How many miles do you think I should put on before dumping the 'rinse' oil and putting in the Amsoil synthetic?
Transmission Fluid: Looks like stock, and while it does not smell burnt, it does not smell nice, either. Is there a DIY way to get ALL the fluid swapped out (including the torque converter)? Planning on Amsoil Torque-Drive.
Transfer Case & Differentials: Pretty standard stuff here. Any tip or pointers from the group? Just planning a dump and replace, but the rear end will get the cover removed and fully cleaned and inspected.

ATMINF · April 14, 2009

As for the engine oil, I would say changing it out with a good syn should be fine and no real need for a rinse out.

As for the Tranny fluid it is a semi-or full Syn from the factory, it is the new DEX 6, and is really good stuff. You can have it flushed, but I always just did a pan drop and swapped out the fluid that way. In all my cars the trannys have held up fine except one(that one lasted at 80,000 miles , but I put a ATI procharger running 7-10lbs of boost on my 1995 camaro at 20,000 miles and for being a stock 4L60E it held up to alot of hard HARD use and finally let go), but that was due to the extra power of the Supercharger and not the fault of the trans. So like I said I think a trans flush is a lttle overkill if you do a pan drop every 25-30K depending on how hard you use the truck. As for the other stuff, well its not hard, just messy. Bring alot of rags and kitty litter to help clean up the mess.

cvandegna · April 14, 2009

I wouldn't waste your time with the "rinse" oil change - unless you really suspect something wrong with the oil that's in their now. Color alone is not a good indicator of oil life or something gone awry.

There's instructions for the full torque converter ATF change on the Amsoil website. http://www.amsoil.com/faqs/ATF_and_Filter_..._Procedures.pdf Differentials and t-fer case fluids are pretty straighforward. My '04 has a drain and fill plug on the rear diff - if you don't suspect an issue I'd just swap the fluid. At only 20K miles, you'd be hardpressed to see any issue before you were feeling one...

Z45 · April 14, 2009

Duramax takes 10 qts per change. You don't need to do a rinse, just a waste of $$.

CAUTION - - You should not use Torque Drive (ATD) in your 900 series, GM spec's Dexron VI ATF. Torque Drive is not for Dexron VI applications. Use the regular Amsoil ATF. ATD Torque Drive is for Dexron III applications..

From Amsoil website

Torque-Drive™ Synthetic Automatic Transmission Fluid (ATD)

Recommended for use in applications specifying Allison® TES-295 or C4, DEXRON® III, MERCON®, Voith G-1363, ZF® TE-ML 14C

The Allison has a spin on trans filter and drain plug. Take 9 qts to change. Someone I know did the complete purge and it took them 6 gallons. Capacity is approx. 13 qts not including the cooler and the lines but by purging you need to run waste some ATF to insure a complete flush. I suggest you consider using a GM branded trans spin on filter, all the other brands are made in China.

Front should take <2 qts but the rear could take as much as 3 qts depending on what ring gear, use the Severe Gear 75W-90 up front. Use 75W-90 for the rear or if you plan on heavy towing you could go to the Severe Gear 75W-110. Make sure truck is on level surface when filling the differentials or your could over fill.

I have helped several friends change over Amsoil lubes in their D/A trucks. They are 2001, 2003, (2) 2004 and 2007 Classic.

Longshot · April 22, 2009

Thanks for the warning about the TorqueDrive. I got the distinct impression from the Amsoil site that TorqueDrive was the thing to use.

I know that the OEM ATF is good stuff, but I am a synthetic believer.

Most people believe that you should get around 20,000 miles before you switch to synthetic. My truck is just below that range now, but I don't know how this truck was driven. With a diesel, I have heard that a proper break-in requires use of engine-braking to really seat the rings. Most drivers do not know how to do this, and I don't know if I'm comfortable making the switch just yet. I've never had a D/A before, so maybe it does engine braking better than other automatic+diesel combos.

Any thoughts?

DBVille · April 22, 2009

Thanks for the warning about the TorqueDrive. I got the distinct impression from the Amsoil site that TorqueDrive was the thing to use.

I know that the OEM ATF is good stuff, but I am a synthetic believer.

Most people believe that you should get around 20,000 miles before you switch to synthetic. My truck is just below that range now, but I don't know how this truck was driven. With a diesel, I have heard that a proper break-in requires use of engine-braking to really seat the rings. Most drivers do not know how to do this, and I don't know if I'm comfortable making the switch just yet. I've never had a D/A before, so maybe it does engine braking better than other automatic+diesel combos.

Any thoughts?

Dexron VI is synthetic. Personally, I use what the guy who designed the transmission recommends. Not the guy selling the fluid.

In numerous vehicles, synthetic is used straight from the factory. Primarily high horsepower gas engines - Corvette, Viper, Porsches, BMWs, and others. I run the same stuff in everything - cars, trucks, lawn mowers.

After 20,000 miles, I think you are more than far enough along for any break in to occur, that is really going to occur. But, anyone that offers advice on this is speculating. Find someone who has data to back up their position. Not just, "this is what I did and I have xxx,xxxx miles with no problem." While that may be true, it doesn't show that what they did is right, just that it didn't fail because of what they did.

Mike2500HD · April 25, 2009

Thanks for the warning about the TorqueDrive. I got the distinct impression from the Amsoil site that TorqueDrive was the thing to use.

I know that the OEM ATF is good stuff, but I am a synthetic believer.

Most people believe that you should get around 20,000 miles before you switch to synthetic. My truck is just below that range now, but I don't know how this truck was driven. With a diesel, I have heard that a proper break-in requires use of engine-braking to really seat the rings. Most drivers do not know how to do this, and I don't know if I'm comfortable making the switch just yet. I've never had a D/A before, so maybe it does engine braking better than other automatic+diesel combos.

Any thoughts?

Dexron VI is synthetic. Personally, I use what the guy who designed the transmission recommends. Not the guy selling the fluid.

In numerous vehicles, synthetic is used straight from the factory. Primarily high horsepower gas engines - Corvette, Viper, Porsches, BMWs, and others. I run the same stuff in everything - cars, trucks, lawn mowers.

After 20,000 miles, I think you are more than far enough along for any break in to occur, that is really going to occur. But, anyone that offers advice on this is speculating. Find someone who has data to back up their position. Not just, "this is what I did and I have xxx,xxxx miles with no problem." While that may be true, it doesn't show that what they did is right, just that it didn't fail because of what they did.

I changed my 6.0 over to full synth on the first oil change. I dont think the break in oil thing is considered a problem now. It was more an issue as people were changing over and getting used to the idea. I have an F-800 at work with an Allison. Its a 93 and a much bigger trans but at any rate I talked to the Allison dealer about changing to synth. Among other things, he said I could change it if I wanted but it would take 2 full changes before the benifit of the syth was realised. Sort of a delayed flush. We have the best lubes and filters in history now...You almost cant screw up unless you leave it in for years. In the 60's and 70's 100,000 miles was a lot. now 200,000 isnt unusual.