ever since my last oil change my MPG's have dropped! I used to get 20 or so to the gallon. I have not changed my driving at all. I thought the snow might have something to do with it but the snow has melted this week (on the roads anyways) and the MPG is around 18 to the gallon. What would cause this? I also got 2 new rear tires, but they are the same as the old one's and same as the front...

 

Maybe the tires are stiffer as being new and need to be broken in. I just had new contis put on back in August and have been getting 20 mpg ever since - winter or summer...

 

A couple of thoughts.

1. The new tires could be under inflated.
2. The wrong weight of oil could have been used.

 

quit bitching. its not that serious.

 

Yea seriously. Some of us only get 12-13 mpg.

 

Winter mix gas? Improper tire inflation? Dirty air filter?

Are you using the onboard computer or your own calculations? Try to verify on your own by calculating at fill-ups.

Check the usual suspects and report back. No its not serious but how many posts on here are?

 

I thought you drove Hummer H1 instead lol

 

I will check these things. I know it's not a big deal but a drop like that might be a sign of a problem to come, so I figure find out what it is now before all hell breaks loose.

 

Agreed. It is abnormal, and therefore should be investigated.

 

Wow. Talk about ****. Sorry. Weather conditions...type of gas, same road everyday...trunk loaded with crud, air filter, under inflated tires??

What was your tire pressure on the old tires? They may have been over inflated givining you that extra mile or two. Try bumping new tire pressure to an extra 10 psi all the way around. See if your mileage improves.

 

Vegas - this happened to me after I let the dealer do an oil change on my X. The dummies put 7 quarts of oil in the engine, and, it killed my gas mileage. I ended up pulling out the extra oil out through the dipstick tube - using a hand vacuum pump designed to bleed brakes.

Regards:
Oldengineer

 

Ah yes, the extra oil in crankcase......forgot about that....good tip thanks!

 

I will check tomorrow and see if there is any extra oil. I know the tire pressure is the same as it has always been, I check it once a week. I will keep you guys updated on what I find. thanks

 

OK, silly question here. I do my own oil changes and have noticed that my motor likes 7 quarts of oil vice the recommended 5.5 (5 for the engine, 0.5 for the new filter). I normally put in 6 quarts of oil, let the car run for a few minutes and then turn off the car and let it sit for a minute or two, then check the oil level. At this point, the oil level is barely at the "MIN" mark on the dipstick, if not below. Adding the 7th quart brings the level up to just under the "MAX" mark (top edge of the hashed area on the dipstick).

I don't see any difference in my mileage that I can attribute to the higher oil level, but I also know that too much oil can lead to other issues. Curious what others think about this (ie, keep the 7th quart in there because that is what the dipstick says should be in there or go with the thought the dipstick is in error and simply monitor the level for any change from the 6 quart level).

 

Thermo, around 6.5 is what I use. Fills it to the full mark, perhaps a little higher. I'm going to go double check though, now you have me thinking about it.

 

I have the same problem. The drive shaft replaced and oil change were performed at the Jag dealer at around 40,000 miles.

Immediately after this, my MPG dropped to 19 from 24...Jaguar told me everything is fine with the car and nothing they did would affect the MPG.

I am still looking for a good dealer around Chicago...any suggestions?

 

That's odd. When I was doing my own oil changes on my 2 X Types - about 6.25 quarts would bring them up to the full mark. When the dealer put 7 quarts in my car, the oil level was way above the full mark.

Regards:
Oldengineer

 

Vegas, just WOT that sumabitch; clean all that crude out.

Yeah, I was doing 6.5 qts in my mom's X-type.

 

What?

 

LOL!

the old "Italian tuneup"....