nagender77

I took my 2010 RX to a toyota dealership in Nov 2012 for a 15k synthetic oil change (0w-20) which is recommended by lexus. When i asked the service rep to confirm the oil viscosity he did mention that it is 0w-20 since they use the same for highlanders. However there has been a gradual drop in the mileage after the oil change. I drive 90% in the city and i used to get 18 to 19 mpg (290 to 304 miles per tank). It gradually fell down by a mile every two weeks and now i am stuck at ~13 mpg (235 miles per tank). I have not changed my driving style and i am taking the same route to work. Does anyone else have similar issue? Do i take it to the lexus dealer to get a fresh oil change. Could this be a tuning issue due to mishandling at the toyota dealership? Please help

Droid13

Did this reference refer to a previous cold January or is this mileage what you typically get in summer? Driving in below freezing conditions, it is normal not to get anywhere near the mileage of summer driving, especially in the city, and extra especially if your trips are fairly short.

nagender77

The mileage dropped by 1 to 1.5 miles immediately after the oil change. I live in Chicago abut nd the weather did not fluctuate much between Nov 12 ( when i had the oil change) and early jan 13.

chuckGS350

I noticed my GS lost about 1.5-2 mpg when winter started.
I think it has something to do with winter blend gasoline.

StillLine

winter blend gas = poor fuel economy

colder temps = poor fuel economy

winter blend gas + colder temps = really crappy gas mileage

If your not convinced and still think it may be a heavier weight oil causing the drop in fuel economy, reach under your truck, drain the oil, replace the drain bolt and pour in 6 quarts of 0w-20.

dwlink

Agree about the winter blend - I've seen a drop in mileage in the wife's RX and my 5er starting this past December. Usually lasts through around March until they ween off the winter blend crap.

Sevn86

What states get the winter blend gas? Cuz i live in Texas and my car doesn't get the mileage it use to. I thinking it has to do with my tires cuz i need to replace them soon, but who knows.

nagender77

This is my 3rd winter in chicago and i did not have any problems during the last two winters. I am surpriised that winter mix drops mileage by 25%

ecr72

It could be unrelated to the oil change. If you want to rule it out, drain the oil yourself and put 0W-20 in it. Or, take it to Lexus to do an oil change. Or, have an oil analysis done (not practical IMO).

It seems unlikely the oil type alone would make such a big difference unless they put in the old 20W-50 or another heavyweight oil. I doubt a Toyota dealer would even have a heavyweight oil on hand in their service department. I just don't see something like 10-30 dropping the mileage by 30%.

vlad_a

Did you check the oil level? It often gets filled up to full or overfilled.

nagender77

I waited a good 10 months after the original post and observed the mileage throughout summer. I do agree that the summer blend gives better mileage. However i was getting an additional <1 mile/gallon throughout summer i.e. about 14 to 15 mpg. The mileage over the since last month again dropped to 13 to 14 mpg. I took it to the dealer and they could not find any issue. The service rep gave me some crappy reasons blaming that it could be my driving style and the the % of city driving. Still puzzled as to how the mileage dropped suddenly after the first 2 yrs. Btw i got an oil change done at the lexus dealership this time for the 20k service. I am calculating the mileage manually using the miles on the trip computer every time i fill up and not going by what the gauge says.