I was thinking of having my 95psd tranny oil flushed out by my mechanic and putting in a synthetic oil in, he uses amsoil. The truck has about 150,000 miles on it and I am wondering should i worry about doing the flush. I've read here that sometimes doing the flush and putting synthetic in it can make it slip, cause problems.

Has anyone done this with a higher mileage tranny and had good results \ bad results? Would you recommend this or not? Thanks

 

Personally I do not like the flushes.....I always drop the pan....drain the TQ...new filter and refill......
I went to amsoil at 290k on my truck with no problems.......I am not sure what the PO used before

 

Do a drop and drain (pan & torque converter) instead of the flush. The flush just mixes new fluid with old fluid, like having a glass of water and as you slowly pour water out of the glass you are also adding water to that glass from the sink, the new water mixes with the old water. Just my .02

 

I have always heard bad things about amsoil. Some people here on this fourm have recommend Royal Purple to me for my manual transmission.

 

I like the flush method, but what do I know about transmissions?

If it is done right it does very little mixing. You will end up with more of the fluid changed than if you drain the pan and torque converter.

It's a myth that a flush or synthetic fluid can damage a trans. Synthetic, like dino oil, will only damage a trans if it is the wrong type of fluid.

 

I believe that dropping the pan and draining the TC are the best way to go. For the extra quart or 2 that is left in the lines, cooler and valve body its not worth it to pull a line especially since these trucks are getting older and fittings don't always like to come apart.

 

New fluid and an dirty/plugged filter just doesn't make sense to me. Especially in a system that does not
'bypass' the oil flow when the filter is plugged. This also give you an opportunity
to wash off the magnet in the pan. A magnet can only attract so many particles before it becomes saturated and allows
the particles to circulate with the oil and clog the filter thus reducing oil flow.
I get many blown trannies in my shop immediately after a flush. Coincidence?

Do you flush your Engine oil without changing the filter? I think not.
At least the engine oil filter will 'bypass' and still allow oil flow.

My uneducated, real world 2 cents.

 

My educated, real world 2 cents says that if the filter is plugged you already need a new trans, not a new filter and fluid.

It is not a coincidence that you get many blown transmissions in your shop right after a flush. There's a reason.

Many (most?) people never service their trans. After a lot of miles they start having transmission problems. Now they decide it's time to change the fluid. It's too late, by the time they noticed it wasn't working right it was too late. They have the fluid flushed, but it the new fluid can't repair the damage that was already done and the trans fails. If they didn't change the fluid it would also have failed, maybe even sooner.