Sludge can build up in the engine because Toyota did not recommend frequent enough oil changes. Lexus will sometimes offer a discount on cleaning the engine if necessary. Owners who changed their oil every 3,000 miles did not experience these problems. This sludge build up can lead to excessive oil consumption.Google+
Car Problem Reports
Toyota Avalon Sludge Buildup on Engine Due to Infrequent Oil Changes
Toyota Avalon Problem
Engine Affected: 3.0L V6
Average Mileage: 100,000 mi (12,000 mi - 150,000 mi)
Visitor, 1998 Toyota Avalon, 3.0L V6, 93,000 mi
sludge in engine.
change oil 3/5000 miles.
Visitor, 2000 Toyota Avalon, 3.0L V6, 150,000 mi
Only cleaner I found that worked (I tried 5 of them) was Auto Rx. follow the instructions completely.
Visitor, 2001 Toyota Avalon, 3.0L V6, 145,000 mi
Sludge accumulated on the underside of the valve covers in spite of scheduled Mobile 1 oil and filter changes every 4,000 miles (Mobile recommends every 7,000 miles). Don't know if the oil was the problem or moisture condensation/oil mix (after engine shutdown)caused the sludge. However sludge eventually got into the valve guide seals and caused heavy oil consumption (1 quart ever 100 miles) which ruined a catalytic converter. Cost of the fix ? Toyota dealer charged $3,416. No idea if it will happen again. Changed to total synthetic Amsoil 5-20 and Amsoil filter. Love the car but thinking about installing a small block Chevy and converting to rear wheel drive (did that to a Nissan Altima).
Visitor, 2001 Toyota Avalon, 3.0L V6
Oil was being blown out the exhaust (white smoke) making it look like it was coolant but the oil was leaking rapidly, not coolant at all. The entire engine had to be cleaned out due to sludge buildup and I am only going to run synthetic oil from now on to avoid the problem again.
Just started useing oil very bad. I took off front valve cover and holes in head was stoped up.. I could not get the back cover off. This is a very good and clean car..Help....
Visitor, 1998 Toyota Avalon, 3.0L V6
sludge stopping up the PCV system causing blown valve cover gaskets and engine had to be cleaned and flushed with valve cover gasket replacement.