Poor peformance after synthetic oil change-over

[ibobby]

Just switched over to Mobil One full Synth oil (5-30w) and it seems as if my truck is running a bit sluggest. Not a very big difference, but a difference that I seem to notice. Also, my mpg meter averages about 12.3 which is a drop from 13.6

I haven't change anything else. same driving habits, same routes, same fuel.
Anyone else notice this. I was expecting better performance.

2007 Denali, 8700 miles.

 

[fco_gonzo]

Thats wierd if anything your mileage should improve slighty. You didn't happen to overfill it with oil?

 

[ibobby]

na..levels are fine. And it was changed by a local auto shop. But I'll check it for a 3rd time to be sure.


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[Black Dog]

Yeah that doesn't really seem possible with the same viscosity in ANY brand, are you sure they didn't slip you some 20w50 or something? That would actually be bad for things like the valve train and such, so I hear.

 

[08Hoe]

My MPG went up when I switched to Mobil 1 full syn - 5w30.

 

[ibobby]

pretty sure...I saw the bottles come of the shelf and get poured into the engine. I've reset the mpg meter a few times while driving, just as I did when I averaged about 13.6

I have to fill up soon and see what happens. I also have to go back for a tire balancing. They rotated the wheels but cant not balance because the shop was out of the inner-wheel weights. This just seems so strange to me. And I'm not a newbie to vehicle performance. I've drove many, owned many, repaired many(DIY).

Maybe the engine needs time to adjust.. I'm also thinking it might be something with the tire rotation(without balancing) that was done.

 

[Gambler]

My first thought was that you overfilled it. Could it be possible the filter they put on was defective and doesn't have the flow rate it needs?

 

[Black Dog]

My first thought was that you overfilled it. Could it be possible the filter they put on was defective and doesn't have the flow rate it needs?

Good point, that would increase pressure pre-filter and labor the pump, robbing power, right?

 

[fco_gonzo]

Are you running your AC? that'll lower your MPG's trust me, my car's ac has been running since late Feb. you can't live with out AC in AZ!

 

[Ickulus]

I got my oil changed yesterday with regular oil. The tech said I shouldnt change unless my oil life indicator is 0 (it read 80%) However I had driven 3500, most of that was across country in one shot....Any insight????

 

[Gambler]

I got my oil changed yesterday with regular oil. The tech said I shouldnt change unless my oil life indicator is 0 (it read 80%) However I had driven 3500, most of that was across country in one shot....Any insight????

The tech was an idiot.

 

[MikeCallery]

Damm is this an interesting thread.

I had installed a Volant CAI and was pleased with the performance. Shortly thereafter went to a Flowmaster 50 SUV and right after that, had an oil change done and I started noticing that my mpg had dropped, very similar to the problem in this thread. It was one of those quick lube places and I had never used them before.

I had wondered if their work could have affected anything but could not imagine how, but this thread leads me to believe I could have had some of the work done sub-par. Wrong filter, wrong oil, not sure.

Maybe it's just worth going back to the first shop I used that has done me well in the past and have them knock it out for $30. Now I'm really curious as the truck has not felt the same since.

 

[ibobby]

Are you running your AC? that'll lower your MPG's trust me, my car's ac has been running since late Feb. you can't live with out AC in AZ!

as posted above....

Just switched over to Mobil One full Synth oil (5-30w) and it seems as if my truck is running a bit sluggest. Not a very big difference, but a difference that I seem to notice. Also, my mpg meter averages about 12.3 which is a drop from 13.6

I haven't change anything else. same driving habits, same routes, same fuel.
Anyone else notice this. I was expecting better performance.

2007 Denali, 8700 miles.

and Mike..

I feel the same exact way. I don't see what they could have done wrong. Used them before with my other vehicles. And I pretty much watched what they were doing. I also thought about the oil filter, tandard Fram model for the truck. Maybe one made specifically for synth oil might work better even though its not required??
Hell...my mpg meter dropped into the 7-8's a few times(short periods) :nonod::nonod: That has NEVER happened since I've owned the truck.

I'll keep checking things and give the engine time to adjust. If it doesnt improve...I'm going back to plain Castro.

:umn:

 

[73shark]

A GM engr on another forum recommend changing at 50% for regular oil and 100% for synthetic oil.

 

[Ickulus]

The tech was an idiot.

That's what I thought....I asked him three times and his response was yup that's what the GM engineers said (with a big smile on his face). Of course this was a Chevy dealership in BFE North Dakota....WHAT AN A$$:smilielol:

 

[Black Dog]

That's what I thought....I asked him three times and his response was yup that's what the GM engineers said (with a big smile on his face). Of course this was a Chevy dealership in BFE North Dakota....WHAT AN A$$:smilielol:

If there's one thing worse than an idiot it's a smiling idiot.
My dealership, who owed me one free oil change, tried to refuse to do it at 2 weeks/900 miles. He said the miles are too low, have you had it for a year... I was like they said I could have it any time, and I want the break-in oil out, and I'll be doing my own changes thereafter. He had to get approval from the fleet manager who sold it to me. It's like until there is a federal law forbidding early oil changes, just STFU and do it! Idiots.

 

[Gambler]

A GM engr on another forum recommend changing at 50% for regular oil and 100% for synthetic oil.

I could see that as a high end, but seriously, changing it early isn't going to hurt anything...like that tech was saying. I change it somewhere around 50-60% w/synthetic personally.

 

[cgeb]

I was averaging 15.9 in mixed driving with dino oil. Went to Penzoil Syn and my MPG went to about 16.5 mixed driving.

Started runnin the AC and the MPG dropped to about 15.8. I didn't makes any other changes so the syn seemed to help MPG but the AC just took it back.:cryin:

 

[S.V.T.]

i'm fairly sure my hoe has been on regular organic for quite some time.. anyone think i should not go to synthetic at 40k miles??

 

[73shark]

Only one I can think of is it will hurt the oil companies if you switch to synthetic.