Synthetic Oil (1999 Rx300) Leak Issue

[mrberl]

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 see some 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 ? any input is appreciated!

-mrberl

[lenore]

You may have sludge in the engine and the synthetic is leaking, there are several options, go back to dino oil, try Auto-RX in the oil and follow their procedure, or pursue the possibility of sludge with Lexus, there is a 8 year 120 day warranty on that engine, unlimited miles.

[RX in NC]

As you just proved, synthetic oil will always find leaks in an older engine that conventional oil won't leak through.

As a rule I would never change to synthetic oil after the vehicle has hit 50,000 miles on the odometer.

Contrary to what some believe, synthetic oil doesn't cause leaks in an old engine but it sure finds them. Unless you're willing to spend the money and time replacing numerous seals to keep the vehicle oil-tight for synthetic oil, it just isn't worth it. Stick with conventional oil in the future.

[tmastres]

As a rule I would never change to synthetic oil after the vehicle has hit 50,000 miles on the odometer.

Well ALL rules have exceptions and IMHO the 1MZFE of the 99/00 would be one for this rule. An engine as prone to sludge as this one should never be run on dino oil.

[gidoks]

Well ALL rules have exceptions and IMHO the 1MZFE of the 99/00 would be one for this rule. An engine as prone to sludge as this one should never be run on dino oil.

I agree with you. I changed mine to synthetic oil, and sure saw some leaks underneath the sump. But that prompted me to loosen the sump and changed the gasket. In the process I found lots of metal debris in the sump and dark oil, though I just put in a new oil;cleaned everything and new synthetic oil.No qualms for months now.

[mrberl]

Well ALL rules have exceptions and IMHO the 1MZFE of the 99/00 would be one for this rule. An engine as prone to sludge as this one should never be run on dino oil.

That's what I figured as well. I was afraid of the sludge problem and that's why I switched to synthetic. I don't mind adding 1/4 to 1/2 a quart every once in a while but having the peace of mind that there won't be sludge (or very minimal). In fact, I just looked today underneath the car and there's no visible leaks anymore (where there were leaks before). I checked right after I took a ride of about 30 mins. Does it make sense ?