Hello all. Two things concerning our 2011 HHR LT,…118xxx miles…

little history of the car…car was non-running with 109xxx miles…exhaust vvt was bad, replaced and cranked right up. Chains and guides shot and very dirty sludged up oil….so before disassembly….4 quarts of conventional 10w-40 and 1 quart transmission fluid in crankcase and new oil filter. Cranked and run to temp several times over 2 months….then all drained and repairs made…including new water pump.
Car ran and runs great. However fuel mileage had dropped off from 37-38 avg at best to 30-34 best. Whats up with that?

Second….thinking I want to change trans fluid and filter, gasket. Dextron VI but what filter gasket recommend? OEM or any good aftermarket brands?

 

OEM is best! The engine oil should be 5W30, could be the mileage issue.

 

understand….I just used 10-40 and trans fluid to clean it out….worked really good btw. I put Castrol 10w-30 Magnatec…Dexos compliant for real oil

 

So, you are just ignoring the label on the oil filler cap? I guess they just felt like wasting money.
10w40 is not good for the VVT valves.

The OEM gasket has a metal inside that makes for good seal the OTC ones are thin rubber. Be VERY careful torqueing the bolts on, 106 lb.INCH/12 N.m, or you will bend the pan.

 

10W30 isn’t recommended either, these Ecotec VVT engines are finicky!

 

I used 4 quarts of 10w-40 only because the one quart of transmission fluid was much thinner viscosity…and all of that to clean the engine.
Since I have put it to work, it has the correct oil in it

10-4 on the gasket

 

Pretty sure I used the correct oil viscosity….was either 10w or 5w-30

 

You now know for next time.

 

37-38 average would be kind of amazing. I wouldn’t believe that without actually recording the fuel pumped and the corrected miles logged. From what I’ve read, most HHR owners (or most other cars for that matter) would be thrilled with 30-34 average MPG. Also, the 2011 is flex fuel. Any chance the ethanol content you’re buying is varying?

If it was Dexos it wasn’t 10-30.

 

…the oil is 5w-30 Castrol Magnatec I used.
the 37-38 mpg was also manually calculated from fuel receipts. Now, to be honest that was between Indianapolis and South Bend, IN where the ground is very flat and speeds from 45-60 ( road construction.) It did it twice, a week apart but not really typical driving conditions. Frankly I was surprised it got that good. Was also top tier fuel (regular) from Costco. Just seems it is more like 30-34 best case now