Worse gas mileage after 1st oil change?

[c5bob]

Recently changed the oil in my V for the first time at 9500 miles. The maintenance minder reported 30% left on oil life, but just couldn't wait any longer. I do mostly highway miles on my 80 mile round trip.

Prior to the oil change I was getting 30-31 MPG consistently with AC on. Since the oil change, I am getting 28-29 on the last 5 fill ups, with no AC. Nothing else has changed, except tire rotation and the engine oil. I understand the original oil has special additives. Is it possible that these additives increase gas mileage by 7%?

[2RedV's]

Recently changed the oil in my V for the first time at 9500 miles. The maintenance minder reported 30% left on oil life, but just couldn't wait any longer. I do mostly highway miles on my 80 mile round trip.

Prior to the oil change I was getting 30-31 MPG consistently with AC on. Since the oil change, I am getting 28-29 on the last 5 fill ups, with no AC. Nothing else has changed, except tire rotation and the engine oil. I understand the original oil has special additives. Is it possible that these additives increase gas mileage by 7%?Coincidence, probably more related to winter gas now being in your area and with colder temps, the car uses more fuel as it tries to warm up. The oil's high moly content aids in faster break-in, not fuel mileage.

[Deano]

I too got one tank of 30 mpg on the original break in oil and after that change at 5,000 miles my milage dropped some. I just yesterday asked the service dept why that was. They had no idea and said they never heard that before and all the original oil had in it was different additives. I asked if it was the same weight oil and they didn't really know. I realize now it is winter but the day after the oil change it got worse. I did talk to another owner and he gets about the same 25-26 i get highway and i do drive 70mph which i know should get better if i slow down to 65. He said he owned two and they get better after about 25,000 miles. Like it in all aspects other than the back seats don't fold down flat like my wifes 07 Toyota Rav 4. Same mpg almost exactly. Ride is slightly better in the Honda. Would rather have the tire on the rear door so i don't have to unload the whole cargo in case of a flat but can live with that. Otherwise a very good car so far for 9500 miles. AWD is great in the winter and the same as the Rav. Interesting to compare them. Wife won't part with her Rav and can't say a bad thing against either one really. Just the rear seat issue for me and i see others say the same thing. Maybe the next redisign will change that. I asked about changeing to synthetic as i like that in my other vehicles and motorcycles and always got slight better milage. Not much input from the service dept. but i think the next change i may try it. Toyota says the same for theirs. Will try it and report later.

[gary696]

.....I asked about changeing to synthetic as i like that in my other vehicles and motorcycles and always got slight better milage. Not much input from the service dept. but i think the next change i may try it. Toyota says the same for theirs. Will try it and report later.

My '08 drivers manual says OK to use syn. as long as oil specs are met and change schedule is maintained.

[Deano]

Dealer said they had synthetic so i think i will try it and see what it does. If the dealer does it then i am covered. Said they thought it was about $10 more per oil change. Going to do the same thing in my wifes Rav as they both have over 10,000 miles now.

[Radar24]

The factory fill oil is reportedly the same as the oil Honda dealers sell. However they add a molybdenum additive at the factory for break-in. Molybdenum is super slippery and has extreme pressure qualities. It should nonetheless only account for 1 maybe 2 MPG more if you are optimistic.

Most high MPG oils contain some molybdenum so if that is what you used the difference should be little. I thought I would mention it. The real cause for the lower MPG is probably something else.

-Rg