Hey everyone,

I have recently purchased a 1999 RX300 and for the past 2000km (1250 mi) I have been running on Mobil1 5W30 Synthetic oil. I have just taken a look underneath the car with a light and I've seen oil leaking in between the seals in various places. The engine has 151,000km (94,000 mi).

Any suggestions? should I switch to a different weight synthetic oil ? should I switch back to dino oil ? should I just keep adding oil ?

any input is appreciated!

-mrberl

 

Search around, some folks are trying Auto-RX with some sucess.
https://www.clublexus.com/forums/sho...d.php?t=290273

 

Did you check for oil leak prior to using Mobil 1?

Mobil 1's website claims that switching to synthetic in an old car will not cause any leak. (Of course.)

 

The engine was absolutely dry before switching to Synthetic. (I checked it all over when my mechanic lifted it) Otherwise I wouldn't have started putting synthetic in it. I believed it wouldn't start leaking as it was very clean.

Any other suggestions? maybe use a different synthetic oil weight ? or will it decrease performance/cause more wear ?

 

If you don't want try the Auto-RX route immediately,

then

Higher weight oil, a W40 will do well, W50, I don't recommend (experience)

Restore oil additive, cheap and normally used to restore compression, but can work elsewhere.

 

Just be careful with using a higher weight oil during winter time...harder to start the car.

 

A true point. A 0W should still do fine, but I have had friends on the net that I have talked to report a little bit harder start using say a W40+ versus a W30-

 

I'd give auto-rx a try.
http://www.auto-rx.com/pages/sealleak_why.html

Supposedly, sludge and/or deposit formation can prevent oil from conditioning the seals, causing them to leak. Removing the deposits will allow the oil to recondition the seals and make it more pliable, preventing the leak.

You'll probably want to run 2 applications since the car is near 100k miles.

My car is running great after one application.

 

How about going back to regular dino oil? Then degrease and hose down the engine bay. LexMex has a great series of photo of his RX getting a bath under the hood.

My 2002 RX300 is now at 99K miles. I have always used 5w30 dino oil. Never used any snake oil or additive. It's driven in the harsh climate and challenging mountain terrain of Colorado. Plus over a year in New York City. The engine has no leak, no oil burning, no vibration, just quiet and powerful performance.

 

Regardless of what the manufactures say, synthetic weeps past seals in older engines and can cause leaks. I think part of it is dino oil tends to swell gaskets and seals a little. I had a very low mileage Mustang (but older) that did not leak a drop when I bought it. I switched to synthetic and it started to leak a little. Switched back to dino and it totally stopped.

 

Which oil company are working for right now?