walter wel

I just bought a 2000 rx300. I was informed of a jelling problem in the engine. The car dealer told me that when the engine doesn't warm up enough jelling occurs. The dealer just spent $3500.00 on top half of engine to resolve problem. Can I use a synthetic oil to prevent it from happening again? Or what else can I do?

HarrierAWD

Welcome to ClubLexus. Do a search on the oil gelling issue, you'll find lots of resource here.

The dealer is incorrect on why the gelling occurs. In hot weather, the top half of the engine can run hot due to narrow coolant passages that were designed to reduce emission. Thus the oil experience rapid temperature change when it drops down to the pan. It tends to gel up when the oil has past its service life.

Synthetic oil is not bullet-proof and will not necessarily prevent all engine issues. Oil change at regular interval is the key for engine longevity. Apparently the previous owner didn't care.

Lexus has extended the RX300 engine warranty to 8 years with unlimited mileage. Your dealer should have installed a new engine instead of trying to fix it.

Lil4X

Personally, I wouldn't worry. Gelling was an issue on a very limited number of engines, and was almost always limited to those that were poorly maintained. Try to get your hands on any service documentation you can on your RX . . . as you would with any car . . . just to support any possible claim.

Replacement of the heads/valve train as a preventive measure is unnecessary, and as you indicate, expensive. While the oil galleries are larger on newer engines, the originals have an excellent history PROVIDED the oil change intervals are observed. Ask your Lexus dealer specifically about the warranty on your engine. A total engine swap would have reset the clock on a zero-time engine. He will probably warrant his work 90 days, but it is up to Lexus as to how to handle the warranty on a partially-rebuilt engine. Whatever the case, you should have at least three more years of warranty remaining.

Harrier is correct in saying that the oil change interval is more critical than the type of oil used. Synthetic oil is slightly more resistant to gelling over long intervals, but it is not immune.

You should not have any trouble with your new RX. The vehicle has proven to be remarkablly trouble-free and a delight to own.

TunedRX300

Synthetic oil definitely help. It has lower ash % and higher flash point than those of conventional dyno juice. Basically you don't want oil to burn and even if it does, has low residue.

"Flash point is the temperature at which an oil gives off vapors that can be ignited with a flame held over the oil. The lower the flash point the greater tendency for the oil to suffer vaporization loss at high temperatures and to burn off on hot cylinder walls and pistons. The flash point can be an indicator of the quality of the base stock used. The higher the flash point the better. "
"% sulfated ash is how much solid material is left when the oil burns. A high ash content will tend to form more sludge and deposits in the engine. Low ash content also seems to promote long valve life. Look for oils with a low ash content."
Quoted from this helpful site
Engine Oil

MB uses synthetic oil straight from the factory and has recommended change interval of 10k miles. Lexus recommends 7500. It is the engine design, quality of oil, and user's oil change frequency that cause the gel problem.

Personally I would go to Lexus only if they are using synthetic oil with an OEM oil filter made in Japan. Not the regular oil change with Castrol dyno juice (recycled) and Purolator or Thailand made filter with Toyota label on. Your engine already has a problem history , let's not put inferior oil and filter to make it worse.

parula

Tuned, yes, with or without a history of engine problems based on oil breaking down,
for me there is no way I can justify using anything but the best synthetic oil in my baby!
The cost is so minor as to not even be worth considering on a $40k car, and even that is probably made up in the alleged very slight increase in fuel economy synthetics may provide. Full synth all the way.
I should add that my dealers will install my synthetic when I bring it in, or they have it in stock, for an extra cost, of course.

TunedRX300

Smart move
I use Mobile 1 0w20 for winter, 5w30 for summer. Use a filter that has synthetic filter material, regular paper can catch >20 micro, synthetic material can catch >10 micro. OEM oil filter made in Japan might has it but you may need to special order it since US and Thailand made filters are the replacement filters Lexus sell. Or you can go for Purolator PureOne, Mobile 1 filter, or Bosch Premium. I am sure you want your filter to trap as much particles as possible.

HarrierAWD

Synthetic oil's flash point is usually about 30 to 40 F higher than conventional oil. Sounds nice on paper, but when there's a malfunction with the engine, that extra 40 F protection won't help.

Using synthetic in an engine designed for conventional has virtually no benefit. It is equivalent of washing cars with bottled water vs. tap water. No need to waste your money. Keep up with the oil change interval and your engine will last a long time.

TunedRX300

I think you will have a hard time to tell Walter that his sludged up engine do not deserve that 45 degree F of extra flash point protection of Mobil 1syn over Castrol GTX dyno juice. RX's engine is not designed for conventional oil, but it is also not designed to gel either.