I am the original owner of a 2001 Lexus RX300. Since the day I brought the car home I have always changed the oil and filter myself every 3000 miles using 5-30 Dino Penz. Never leaked even a drop of oil or gave me any indication of sludge. The car now has 180,000 miles on it. Following shoulder surgery 4 months ago I couldn't change the oil myself so I took it to a reputable mechanic. Not long thereafter the engine began to drip oil onto my garage floor. Double checked my oil change invoice and found that the mechanic had used 5-30 SYNTHETIC oil for the change.
I immediately suspected this switch as the cause but checked all the major synthetic oil makers web sites and virtually all of them said that early synthetics could cause leaks in an older engine but the modern ones could not due to newer formulations and additives. So, back to my mechanic for $400 valve cover gasket replacements. Engine still drips and now my mechanic wants to change the rear main seal for lord knows how much money. After finding this Auto-RX website and reading extensively, I'm convinced that the synthetic oil cause my problems. I'm looking for advice as to what I might do now given the spot I'm in. Any advice much appreciated.
Redlyne
-- Edited by Redlyne on Thursday 20th of February 2014 01:19:27 PM
Hello clean your engine using the Auto-Rx Plus (1 bottle) basic cleaning application.
When done go back to a good mineral oil (Castrol GTX) leaks should stop within a few hundred miles. If you think you really have a rear main seal leak ?? try "Basic" application first. You have diagnosed your problem.
Synthetic oils tend to make rear main seal polymers a bit more flexible and has a bit of a softening effect on the seal. It is quite possible that you have a build up of oxidized oil on the crankshaft journal and some packed up under the seal itself. By cleaning with Auto-Rx in a conventional or mineral oil based you can achieve 2 things. Dissolve oil related residue from the jurnal and the seal, then allow the mineral oil to stiffen the seal and help it find its old memory and perform the seal function. You may also want to check out the PCV valve on this motor. A sticky or stuck PCV valve will trap positive pressure inside the motor cavity and force oil out of the weakest seal(s).
