I am trying to conver my Trans fluid, Engine Oil to a full syntetic, Amsoil. I am worried about this Change cleaning out the engine sluge or even crap in the trans. Could it blast crap into my oil pump? Mess up my trans? I see some guys on here have changed over already, how many miles did you have on your truck when you switched over?

I switched to Rotella T synethic oil when I bought my suburban with 142,000 miles on it. I dont have any problems because the things you are worried about are myths from when they first came out with sythentics decades ago. Do it and dont look back.

X2."Myth" If you have serious varnish accumulation in the trans any new ATF will start to emulsify the varnish.There is a large amount of ATF to to disperse the varnish. Engine is not as likely to have any sludge,as the engine oil is changed by miles driven on some mileage chedule.Much less miles per interval than trans. T

I had 235k or maybe a little more on my truck when i switched it to synthetic motor oil. It does great and it does not leak anymore now than it did before. I noticed a pretty good difference in it. I cant say how synthetic ATF would be but i have been told it could clean up the valve body in the trans from any sludge and varnish and possibly clog it up somewhere along the line but i don't know if thats true or not. I will say tho that my truck now has 250k on it and the trans fluid has NEVER been changed. It is dirty and could probably use to be changed but, i'm afraid that new fluid might do it in at this point so i think i'm just going to leave it alone.

I would just change out using regular ATF and then do it again 5k miles later. You don't need to go to synthetic.

Just change the filter every 2500 miles or when it gets dirty whichever comes first and keep topping it off.

When the oil staysclean for a reasonable amount of time the sludge has been cleaned out.

The synthetic will clean out the sludge but it won't do it all at once.

I don't recommend oil flush products unless you will be rebuilding the engine soon.

If it's went this far on regular type oil why would you want to change?

I have seen transmissions crap out after an oil change. On high mileage transmissions I just change the oil in the pan to be safe. My stuff, I pull the cooler line looose after the change and pump out all the old oil.

Change once a year. Never had a trans go out yet.

I will say tho that my truck now has 250k on it and the trans fluid has NEVER been changed. It is dirty and could probably use to be changed but, i'm afraid that new fluid might do it in at this point so i think i'm just going to leave it alone.

Did you buy it new? are those all your miles? Or did a PO change the trans juice B4 you got it?

I don't think you have anything to lose by changing the ATF, only to gain. Just think of all the money you've saved by not changing it! Even if it blows up (unlikely) you've gotten your moneys worth out of it.
The new dex is as good as some synthetic, IMO. Gen Biltstein is the final authority on this at DP, isn't he?

Did you buy it new? are those all your miles? Or did a PO change the trans juice B4 you got it?

I don't think you have anything to lose by changing the ATF, only to gain. Just think of all the money you've saved by not changing it! Even if it blows up (unlikely) you've gotten your moneys worth out of it.
The new dex is as good as some synthetic, IMO. Gen Biltstein is the final authority on this at DP, isn't he?

I bought it from my boss who is the P.O. He had it since it was new, says its never been changed. He said the chart in the owners manual doesnt say anything about changing the transmission fluid at any interval (atleast up to 100k which is as far as the chart goes) so he never changed it. I'm going to call the transmission shop and see what they have to say, but i'm awfully tempted to leave it alone.

I like Diesel Pros way of changing the ATF.Fine tune your ears for whining,low level ,almost inaudible sound of thick ATF/or some level of filter pluggage.Cold start up whine is a typical of some level of filter pluggage. Think about power steering whine as an example. As a former 23Yr auto trans shop owner/operator I would buy Mr Goodwrench ATF & new AC Delco filter from the dealer or AC delco warehouse & change the fluid & filter. If you want to you f could force all the ATF that will come out of a disconnected cooler line.Do this while hot & shut off the engine when the ATF flow drops off .I would then refill with less cost new ATF & dilute what dirty ATF left in the converter & run the engine again.Raise the rear wheels & make multiple manual up shifts & reverse selection to get all the valves & chambers purged of the old ATF.Then install what ever ATF you want to use.Current GM DEXRON product is the best ATF on the market IMO. GM at one time was ready to claim "for the life of the vehicle"on new vehicles.Idon't know what current think is.But it is your money,do what you want to.

My engine got synthetic in it after the break in period after the rebuild, and I haven't used anything but synthetic since.

As far as my transmission goes it had about 125,000 kms on it when I changed the fluid to synthetic, and haven't had an issue.

I remember in a previous thread that Amsoil makes a product for a flush before switching to amzoil. Check with a dealer.There are several dealers that are vendors on this site.

I switch my truck over at 80,000km to all amsoil and never looked back. I change my engine oil every 12 to 15k and oil sample says oil is still in good shape. Noticed a change in the truck in -35 c weather. Go for it and you wont regret it.