Thoughts on my Oil Choice

[stevey_frac]

Hello All,

I'd like to get some input on my plans, as i've not been doing this kind of thing very long.

I have a 2007 Cobalt with the 2.2 Ecotec engine. I'm told they're pretty easy on oil. At present i'm going a 5k miles on the oil, although the oil life monitor would let me go 10k. I do all highway driving, and it's rare that i start my car without driving at least 60 miles.

I change the oil at 5k miles because my fuel economy starts to go down, and i'm convinced that the oil is thickening. Every time after changing the oil, it bounces back up. Now we're not talking huge variations, perhaps 3-4%.

Anyways, my plan is to use Amsoil SSO 0W30. Not only do i believe it will provide better protection, and be easier on cold starts (i'm from Canada) I would be comfortable going the full 10k on a synthetic oil. Once my car is out of warantee, which it will be in a year and a bit, I want to do about 20k miles per oil change. That would reduce my oil change interval from once every 6 weeks to once every 6 months.

Thoughts?

-Steve

 

[Drew99GT]

I think you're spot on! I personally wouldn't do 20K, even with SSO, without a UOA, but 10K according to the OLM will be a piece of cake for this engine and oil combo.

 

[Quattro Pete]

What oil brand/grade are you using now?

Maybe figure on changing the oil filter half way through the interval when you'll be pushing 20k mile OCI.

 

[stevey_frac]

Would it be worth it to get a UOA at 10k and see if i could extend it further? Or just don't worry about it and do a 10k OCI?

10k would put me at about 3 months, which isn't terrible i guess.

 

[stevey_frac]

Originally Posted By: Quattro Pete
What oil brand/grade are you using now?

Maybe figure on changing the oil filter half way through the interval when you'll be pushing 20k mile OCI.


I was just using whatever the dealer carries in bulk. 10w30. I tend to drive low RPM high load for fuel economy reasons. I rarely exceed 2k RPM in town. So i don't think the oil shears down very much, but instead tends to thicken as some of it boils off.

 

[Drew99GT]

Yea, it would probably show that 15K+ is doable since you do all highway driving.

 

[Quattro Pete]

I would say that the type of driving you're doing (putting high load on the engine at low RPMs where you don't have much torque) is probably more stressful on the engine and oil than otherwise. Does it really result in better fuel economy? I'd figure that accelerating at low RPMs would take you longer to reach the the desired speed, hence more time spent burning more gas.

 

[ericthepig]

I didn't follow the math of a 5k OCI being done in 6 wks and 10k in 6 months. (?)

Meanwhile, very good oil choice. I would do exactly as you're planning to do (and I've done it - but back with previous versions of Amsoil and when I had a long hiway commute). I would recommend doing 15k on the SSO, then do a UOA (sample thru the dipstick -just get some acquarium tubing) - if the TBN is still good and the wear metals are reasonable - this will give you proof of concept on pushing on to 20k. If all is well, then just start sampling every couple of years.

 

[Quattro Pete]

Originally Posted By: ericthepig
I didn't follow the math of a 5k OCI being done in 6 wks and 10k in 6 months. (?)

I think he said 20k in 6 months.

 

[stevey_frac]

Originally Posted By: Quattro Pete
I would say that the type of driving you're doing (putting high load on the engine at low RPMs where you don't have much torque) is probably more stressful on the engine and oil than otherwise. Does it really result in better fuel economy? I'd figure that accelerating at low RPMs would take you longer to reach the the desired speed, hence more time spent burning more gas.


At 1500 RPM the available torque from the engine is about 20% of the torque available at the torque peak. If the engine is built to withstand the force of 100% of torque peak, I see no reason why there would be any strain at all on the engine when putting less then 20% of the strain on the engine.

If you really want to talk about the fuel economy gains you have to take a look at brake specific fuel consumption, where you make a map of engine load vs rpm, and then monitor the fuel required to achieve a certain a certain power output as measured at the flywheel. At very low engine load, the parasitic drain of the accesories causes available power to be very low compared to fuel consumed. At very high engine load, many engines will begin to run rich to prevent detonation. Thus you want to run as high of an engine load as you can without causing your ECU to go into a fuel rich condition. Similarly, at very high engine RPM, the engine no longer behaves as an idealized otto thermodynamic cycle because the expansion of the combustion volume has become significant compared to the expansion of the flame front, and many cars will not put more spark advance then a certain amount to prevent damage to the engine in the event of a sensor failure. Also, engine friction increases with the square of the engine speed. So the best you can do for a fuel economy standpoint is to run at higher load, approximately 75-85% engine load, and at as low an RPM as you can manage.
Compared to normal driving this will typically result in 20% fuel savings. I always beat the EPA rating for my car. Even the old ratings, before they made it trivial to beat.


So... in summary. Yes. It saves fuel.

 

[KW]

I have an 06 Cobalt with a 2.2 as well and use Amsoil ASL 5W30 in it and change on the OLM. Your highway miles are very easy on oil so I would be tempted to use the XL 5W30 and change the oil on the OLM.

 

[FZ1]

You're right. The economy drop indicates the oil is done. Your oci is correct for that oil, in your car, with your driving,etc. Experiment with slightly better oils in sequence and change them out when the FE drops. Pick the best performer.

 

[Durango]

Originally Posted By: stevey_frac
Hello All,

I'd like to get some input on my plans, as i've not been doing this kind of thing very long.

I have a 2007 Cobalt with the 2.2 Ecotec engine. I'm told they're pretty easy on oil. At present i'm going a 5k miles on the oil, although the oil life monitor would let me go 10k. I do all highway driving, and it's rare that i start my car without driving at least 60 miles.

I change the oil at 5k miles because my fuel economy starts to go down, and i'm convinced that the oil is thickening. Every time after changing the oil, it bounces back up. Now we're not talking huge variations, perhaps 3-4%.

Anyways, my plan is to use Amsoil SSO 0W30. Not only do i believe it will provide better protection, and be easier on cold starts (i'm from Canada) I would be comfortable going the full 10k on a synthetic oil. Once my car is out of warantee, which it will be in a year and a bit, I want to do about 20k miles per oil change. That would reduce my oil change interval from once every 6 weeks to once every 6 months.

Thoughts?

-Steve



Steve,

For economy sake have you considered trying a 0W-20 oil??? From what I've heard Amsoil is a fantastic oil to use so if your happy with it then that's for you. Personally I'm a Mobil 1 guy and seeing the new magazine ad regarding their new green cap economy oil is very interesting.

In about a month I'm considering a new Chevy Impala "SS" for myself and as always plan to use M1 after the initial break-in period for this engine (which I don't know yet). Currently my guess is that it'll take a 5w30 weight oil but eventually want to use a 5W-20 version to try and gain some additional highway mileage even though it'll be minute.

Good luck to ya and cross your fingers for me. Here in Los Angeles it's hard to find the SS at the dealerships.

Durango

 

[addyguy]

Use the XL 5w30 and change according to OLM. Wait until out of warranty to go to more 'exotic' oils...you want to stick to an actually API-certified oil for the warranty period, and the OLM-dictated chage schedule.

 

[ericthepig]

Originally Posted By: Durango
In about a month I'm considering a new Chevy Impala "SS" for myself and as always plan to use M1 after the initial break-in period ..


My brother owned a 65 Impala (this is around 1970). Beautiful red. Four barrel. Our next door neighbor (at the time) older teenager got himself a '66 SS Impala. Those were the days.

Now back to the OP. Use M1 or Amsoil.

 

[1WildPig]

Ahh, I had a 65 SS Impala in '74, red with a white top...yep, those were the days...sorry for the hijack, just reminiscing...to keep it on oil, I changed it every thousand miles! > all city (haha..town) driving...

 

[Audi Junkie]

Isn't that a dino oil application? Why use anything else?

 

[tropic]

Originally Posted By: stevey_frac
At 1500 RPM the available torque from the engine is about 20% of the torque available at the torque peak. If the engine is built to withstand the force of 100% of torque peak, I see no reason why there would be any strain at all on the engine when putting less then 20% of the strain on the engine.

I'll add something to consider: CFM of the oil pump @ 1500 RPM Vs. CFM @ 5,000 RPM.

 

[stevey_frac]

Originally Posted By: tropic
Originally Posted By: stevey_frac
At 1500 RPM the available torque from the engine is about 20% of the torque available at the torque peak. If the engine is built to withstand the force of 100% of torque peak, I see no reason why there would be any strain at all on the engine when putting less then 20% of the strain on the engine.

I'll add something to consider: CFM of the oil pump @ 1500 RPM Vs. CFM @ 5,000 RPM.


Because of the nature of pumping oil, I would contend that at low RPM, there is more oil flow per revolution then at high RPM. There is more oil pressure at higher RPM, but who cares about pressure. Oil flow will not increase linearly with pump speed.

 

[stevey_frac]

Originally Posted By: Durango


Steve,

For economy sake have you considered trying a 0W-20 oil??? From what I've heard Amsoil is a fantastic oil to use so if your happy with it then that's for you. Personally I'm a Mobil 1 guy and seeing the new magazine ad regarding their new green cap economy oil is very interesting.

In about a month I'm considering a new Chevy Impala "SS" for myself and as always plan to use M1 after the initial break-in period for this engine (which I don't know yet). Currently my guess is that it'll take a 5w30 weight oil but eventually want to use a 5W-20 version to try and gain some additional highway mileage even though it'll be minute.

Good luck to ya and cross your fingers for me. Here in Los Angeles it's hard to find the SS at the dealerships.

Durango


I didn't see this the first read through, so i thought i would reply to it. I'm concerned about using a 20 wt oil in my car. I want this vehicle to last a good 500k kms at least, and i'm worried the 20 is a tad light. That's why i went with the 0W30.

-Steve