Hey,
My 92 LS400 (163k, full Lexus history) used to get around 15-20 mpg around town, and up to 32 mpg when put on cruise control at 70 mph.
However, in the last year or so, the car gets the same city mileage, but I can't go past 21-22 mpg even when cruising at 65 on cruise control. I don't understand!!!
Air filter was replaced in Feb 2003, as was the oil and filter.
Anyone got any ideas what might be doing this? At the last service, it went from semi-synthetic to Castrol RS.
The only thing I can think of is that the spark plugs are 5 years old now, and according to the service schedule, should be replaced now. Do they really make such a difference when they get old and tired?
Thanks in advance,
P.S At last service, the bearings in idle tensioner were making the engine very noisy - I don't know if that is related?