03 Burb - Trans flush and change to synthetic

My Burb has 102K miles on it and being that I bought it used I don't know how the orginal owner drove it.

I was thinking when I get the trans filter and fluid changed to go synthetic.

Has anyone had any bad experience with doing this?

Also am considering going synthetic with the diff fluid. Any thoughts?

Thanks in advance.

Sandman

My Burb has 102K miles on it and being that I bought it used I don't know how the orginal owner drove it.

I was thinking when I get the trans filter and fluid changed to go synthetic.

Has anyone had any bad experience with doing this?

Also am considering going synthetic with the diff fluid. Any thoughts?

Thanks in advance.

Sandman

The diff should already be synthetic (should be a blue tag saying so near the fill plug). My 2000 Yukon is that way but maybe they changed it for 2003.

I have not used synthetic in the tranny so I can't help you there. It would be a good idea to change the fluid and filter if you don't know how long it has been.

//2000CAYukon

Thanks for the reply, I will check the diff for the tag you mentioned. Still would like to hear from anyone that has did the Trans and filter with synthetic.

Sandman

At about 32,000 miles, I changed the fluid in the rear axle to Royal Purple. With the gasket and three quarts, it set me back about $37. I was glad I didn’t wait, as the magnet on the diff cover had a lot more metal shavings than I would have expected. Shortly thereafter, I talked the dealer into flushing my transmission with the Royal Purple. I paid a flat fee of $75 and brought all the fluid. The tranny only holds about 12 quarts, but he wanted me to bring 14. It was a little tricky, as the dealer machine is set up to pull from the GM 50 gallon drum of Dextron. We used a 5 gallon Home Depot bucket to suck the new Royal Purple into flush machine. That was last year, and I finally got around to replacing the filter and gasket. I did that about three weeks ago. I bought the AC Delco filter from my local Midway, along with a neoprene AC Delco gasket. I had to put in another 5 quarts of Royal Purple. I’m at 43,000 miles and no problems or issues with the synthetic. I’ve used Mobil 1 in my engines for almost 20 years. I’m sure either brand will offer superior protection over their conventional counterparts. Hopefully, you can make the change without any issues. That would be my only concern. Changing fluid types with so many miles, or even a flush on a tranny with no other service intervals could cause other problems, due to the age of the seals or lack of maintenance.

I know about Transmission flushes,more bad than good and do not ever have one done.When it flushed with the machine,it is back flushed and where does the dirt and crud go?In the valve body causing sticky valves and more problems down the road.The machine uses more fluid and I know a transmission shop that loves doing valve body cleanings and rebuilds after a flush is done.I am not giving the name of the place or thier phone number.I have replaced one transmission after it was flushed so far after fixing it once which did not work.The best thing to do to an automatic transmission is change the fluid and filter

Hi wafredrick,

so if you suggest just doing a trans filter and fluid change, would you change to synthetic? And if you do a fluid change to synthetic, how would you make sure you got all the dino fluid out (or at least 98%)?

I wouldn't think a partial mix of dino and synthetic would be a good thing.

Thanks for you help.

Sandman

You can mix synthetic with dino oil.I know a couple of my father's friends that put in one quart of synthetic engine oil with dino engine oil when doing an oil change.They have not not hurt the engines yet and runs good.Here is a real flush,a line flush which is better than the machine.Disconnect the bottom line from the radatior putting a hose on it pointing to a pan.Start pouring fluid in while running making sure not to run the transmission dry.Stop when it is clear.The advantage is you can see the condition of the fluid and removes the dirt,crud out.The machine uses more fluid and that is a disavantage.I hear more horror stories after a flush with the machine

Do this line flush when running the vehicle.

Hi Wafredrick,

I have heard of doing a trans flush by disconnecting the return to the trans like you mentioned.

I will probably go this route to do a trans flush and change to synthetic.

Thanks for suggestions.

Sandman