Tranny fluid. Flush or just change??

[harlo]

When I bought the truck with 90k I had it flushed. Now I'm up to 120k now and not sure if I should flush or just change. What do you guy do every 30k?

[WD40]

Change it and both filters.
Doug

[Evil Eye]

That's the procedure in the service manual as well.

[smokersteve]

check out my link for changing the trans fluid.

[harlo]

Thanks guys. Good link smoker steave!

[tuckman]

I drop the fluid in the pan every 10k and add 7.5qt of new fluid. Then at the 30k mark I drop the pan and change both filters.

Anybody think that is a bad plan or should throw a full flush in there somewhere? Sorry for the partial hi jack.

[Evil Eye]

Originally Posted by tuckman

I drop the fluid in the pan every 10k and add 7.5qt of new fluid. Then at the 30k mark I drop the pan and change both filters.

Anybody think that is a bad plan or should throw a full flush in there somewhere? Sorry for the partial hi jack.

The service procedure is to drain and refill every 30k miles and change the bypass filter every 15k miles. It's worked just fine for my transmission for over 120k miles.

[smokersteve]

Originally Posted by tuckman

I drop the fluid in the pan every 10k and add 7.5qt of new fluid. Then at the 30k mark I drop the pan and change both filters.

Anybody think that is a bad plan or should throw a full flush in there somewhere? Sorry for the partial hi jack.

So you change ~7.5 quarts every 10,000miles, then on the 3rd 10,000mile increment ( or once every 30,000miles) you change ~7.5 with both filters. Right?

I do think you are waisting money/time doing that procedure, but that is "good enough" for changing the fluid.

7.5 X 3 = 22.5 which is more than the capacity. BUT each time you replace 7.5 quarts you are replacing some of the new oil you just put in 10,000 miles ago... This is where I se it being wasteful of money.

Do you drop the pan every 10,000miles?
Do you clean the magnet?

[tuckman]

Originally Posted by smokersteve

So you change ~7.5 quarts every 10,000miles, then on the 3rd 10,000mile increment ( or once every 30,000miles) you change ~7.5 with both filters. Right?

I do think you are waisting money/time doing that procedure, but that is "good enough" for changing the fluid.

7.5 X 3 = 22.5 which is more than the capacity. BUT each time you replace 7.5 quarts you are replacing some of the new oil you just put in 10,000 miles ago... This is where I se it being wasteful of money.

Do you drop the pan every 10,000miles?
Do you clean the magnet?

Yes on the third interval it is another 7.5qt and the magnet gets cleaned then along with the filter in there. The toilet paper roll gets changed when the pan is dropped.

On the flip side of the coin, I am replenishing the additives in the trans oil every 10k. The only thing I am not sure of is I the trans shears the fluid down and that is why they call for the service interval of 30k.

[howell_jd]

If laboratory analysis of the transmission fluid is incorporated with the service interval the answer is validated with objective data otherwise it is an academic discussion with subjective opinion. I strongly encourage the use of a trusted over-the-road laboratory (perhaps one that provides while-you-wait analysis) or one of the mail order laboratories. I have used these three:
Blackstone Labs
Predictive Maintenance Services, Inc.
Oil Analyzers, Inc. - Oil Analysis, Oil Testing Services
All three are fantastic and have distinctive advantages/disadvantages. Oil Analyzers, Inc. is AMSOIL's lab. Predictive Maintenance Services has the lowest cost per analysis but it is a pay in advance so you don't want to lose those sample bottles! Blackstone provides their sample bottles for free readily. As I said, I've used all three and feel comfortable saying that all have great support and genuine professional analysis; you can't go wrong with their insight!
Ultimately, the service manual is the starting point. Laboratory analysis validates or invalidates any personal adjustments to the service interval, service technique, or service options.

Keep it cool!

Jonathan