jcjr

Hello,

I have a 2001 AWD RX 300 that i purchased 3 years ago with 60K miles....

It now has 85K miles with no major issues.....I was "semi-stored" in Phoenix for the first year....it developed a leak from the rear main seal....I was new to the forum and did not know about Auto-RX

I had the seal replaced at a honda dealer for about $600..

I just found a Jiffy Lube receipt stuufed in the owners manual from when the car had 30K miles....

An oil change was done with mobil 1...in the comments section it says "REAR DIFFERENTIAL LEAK"..

I am not aware if this was ever addressed by the previous owner....the car was a trade-in at 30K at a Ford dealer....

I have not noticed any leaks since the rear main seal was fixed..

Any thoughts would be appreciated!!!!

Lexmex

I am confused. You mentioned rear differential, which is on the rear of an AWD RX300, but you also mentioned a rear main seal, which is actually up front by the torque converter and flywheel, which one are we talking about?

jcjr

Sorry for the confusion....I was just giving a brief history of the vehicle since I owned it...the rear main seal was replaced...

I just found the Jiffy Lube receipt with 30K miles that said "rear differential leak"......this is what I am conjcerned about....again I do not know if it was taken care of before I bought it..

Lexmex

Well, I used to have a leak with my transfer case up front, leaked out gear oil. You can still see the stains here in this picture and even on the exhaust.

Similarly, if you have a leak on the rear differential you might expect to find similar looking stains on your rear differential. However, it is possible that the leak could be slow moving and drip where it might not be noticed. Next time you drain out your rear differential, I'd measure the amount that came out. There are seals on either side that can weep out, though I don't think in my years here on CL I have heard of an RX300 with a leaking rear differential, but I sure have with transfer cases.

jcjr

Thanks Lexmex,

When you say "used to" have....did it go away on its own???

I will look under the car when I get a chance.....

What would be the consequences if it was not fixed all this time...

To be honest I have not changed the rear differential fluid...just oil changes and a tranny fluid drain and fill....

Lexmex

One trick I used for some time was to use some heavier 75W140 oil I got at BMW (I didn't have much of a choice in synthetics in Mexico for a variety of reasons) and that stopped it. Then when I had my transmission out to replace the transmission pump, my uncle took the seals out of the transfer case and put in new ones, that seemed to alleviate the problem even after I went back to 75W90 (Pennzoil Synthetic) and haven't noticed an issue since.

Well, in theory, if the oil seeped all the way out, eventually the gears would overheat, warp and crack. I think the one time I was able to measure the leak over a year when I still had the problem in my transfer case, it was like .200 liters per year and it hold .9 liters, but that's a rough estimate.

In addition, all oil shears over time (this is more precisely confirmed via oil analysis), and eventually the oil can seep out through a small crevice.

Gear oil is perhaps the longest lasting fluid in the car (well maybe window washing fluid).

jcjr

Looked underneath the car last PM and so nothing concerning....I will assume that it was fixed....it has been almost 60K miles since that Jiffy lube receipt so a major problem would have shown itself by now...