colenzae

250,000 miles recently started getting blue smoke at start up. On the highway, burns about a quart every 650 miles. I'm thinking valve guides? If so, is that something that can be done without removing the heads?

Lexmus

Could be the rear valve cover as well. It is a well known issue with the RX300 that will burn oil as a function of speed.

https://www.clublexus.com/forums/rx-...lve-cover.html

I burned as much as a quart every 300 miles on the interstate. Installed an oil catch can and confirmed it was the valve cover as it collected a large amount of oil. I replaced the valve cover and the oil burning stopped.

So before doing anything major, install an oil catch can between the PCV valve and the intake plenum and see if you collect significant oil over a reasonable period like I did. I bought this inexpensive one and it worked well, but I used 3/8" transmission hose instead of the ones supplied.

If so, you will have to replace it with the 3rd gen version of the cover. Is is a major pain to do yourself, however labor for a mechanic will run upwards of $600, not including parts. All info is in the above thread.

sktn77a

iTrader: (2)

Do a straight compression test and a leakdown test. This will identify/eliminate some sources of the oil burning.