Anyone ever flushed their rear-end

[SlurpJ]

I am 100% positive that the oil in the rear end of my G9 has never been changed. I have had water well above the tires many times and figured I would change the diff oil. Would it be alright to flush it out with say diesel or even something like Sea Foam. Maybe fill it, run it down the driveway once or twice, drain it and fill with oil? Also what does everyone use for diff. oil?

[Mike Mac]

I changed mine with regular Valoline gear oil for a couple months, then changed it to synthetic Valoline.

[daveswaves]

Originally Posted by SlurpJ

I am 100% positive that the oil in the rear end of my G9 has never been changed. I have had water well above the tires many times and figured I would change the diff oil. Would it be alright to flush it out with say diesel or even something like Sea Foam. Maybe fill it, run it down the driveway once or twice, drain it and fill with oil? Also what does everyone use for diff. oil?

Have not done mine yet but it is on my list for the rebuild. Diesel would certainly clean it out, however, I am not sure that the seals are compatible with diesel, they may swell. When I clean out my outboard lower ends I use paint thinner/varsol since I know the seals are compatible. I think your choice of oil should be based on your usage. for example, I will be using mine in the winter months too so will go with a multigrade oil.

[Mike Mac]

I'm pretty sure the bearings are sealed bearings, so I wouldn't put any solvent based fluid in it. Will get into the bearings and wash out or delute the grease. I jsut used oil and run it for a period of time. Then change it warm.

[thecurti]

I did the same

I drained mine, filled with regular oil, ran a few days, then drained and put in synthetic gear oil

That was a few years ago, but it will be years more before I do it again. I dont think I could wear the synthetic gear oil out

[daveswaves]

To clarify my post, there are 5 oil seals in the G9 transmission. These are the ones I would be concerned about with diesel. Any bearings inside the transmission are open and designed to run in the oil. The wheel bearings are not in contact with the oil..unless one of the oil seals lets go. I wholeheartedly agree with flushing the transmission with a light weight oil, running it, draining it, and replacing it.

[Mike Mac]

Dave, I think the inner bearings are sealed like the outer ones. Don't know for sure, never had one apart. But the tranny oil is contained in the aluminum case only, not the axle tubes,so I'm guessing the bearings are sealed units. At any rate, oil is the safe way to go, and still acheive the results. Just my .02.

You may know different, if you've had one apart. Not tryin ta argue, just playin it safe with the knowledge I have. Or think I have.

[scottyb]

WhOA !!! This thread title threw me for loop
For a moment here I thought I had logged onto the wrong dang website......

[Mike Mac]

Scotty, you know, are the axle bearings sealed bearings or is there a seal on the outside of the case? I've pulled the axles before and don't recall seeing a race on the axle for a seal.

[spriddle]

Good idea to change the rearend fluid once a year unless you get into water and then it needs to be checked and changed if needed. Any good 75w90 gear oil. I wouldn't flush with anything. Simply drain and refill.