GC Gold costing me pure $GOLD$

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Feb 4, 2005
I hate to admit this, but GC gold is costing me money. My MPG has dropped 2, or maybe even close to 3 MPG. I'm almost done with my tank, so I don't know exactly yet. I do know however that I am almost 50 miles under what I am usually at. I don't consider external conditions like driving habit, weather, gas type, etc. to be a factor since those have been constant. The oil is the only differing factor.

On the good side though, GC gold has done wonders for my car. Very quick starts, quieter engine, and good protection. The dilemma now is whether GC is worth the extra $11.xx a month in wasted fuel.
That's one of the reasons it was only in my car for 1 OIC. My mpg was down 1 to 2 mpg and since I have switched to Chevron it has gone back up to where it was(still blah due to the winter gas)prior to filling with the GC.

On the flip side my UOA on it showed it was a pretty decent oil but not at the expense of lost mpg. I know, I know....nothing scientific but you don't need to be a rocket scientist to see that if you were getting 31-32mpg pre GC and then 29-30 during GC and after it comes out you are back to 31-32 mpg that it had something to do with it.(what an awful sentence..that didn't flow well did it)

Hey I don't doubt it is great stuff but just didn't seem to jive with the 1.8 1zz, that's all.

the smaller the engine, the more viscosity would have an effect on efficiency, right? It seems like this would be true anyway...I don't know it for a fact. I JUST put it in my 2.5 Subaru engine. I'll keep it in for the duration even if it does drop the mileage...because the oil costs a lot, the filter costs (assuming you'd change it too), and the new oil costs. For me, 3 mpg change not make me change it early.
I simply don't see how the viscosity of GC could by itself result in a decrease of 3 mpg (~10%). Comparing a synthetic 0W20 to a conventional 15W40 I could possibly see it.

Also, I wouldn't even begin to entertain this original premise if you didn't keep precise records of every tank of gas and mileage for the entire prior oil period, GC oil period and post oil period.


Going from 5W-40 oils to GC in my VW 1.8T engine did NOT change my gas mileage, but it did make starts easier and improve turbo lag. Weird but true.
my 4.7L V-8 dakota the mileage has stayed the same. city 14 to 16 and hwy. 18 to 20. I had 5w30 M-1 prior. maybe 4 bangers has a harder time pushing a thicker 30 weight oil. or they wanted to make sure to fail GC from the begining.
My 4.3 V6 1/2 ton 5 speed truck didn't loose any mileage and may have even picked up a .5 mpg. Either way, I'm not giving the stuff up - the truck just loves it. I'm thinking I might try the Belgian 5w/40 in the summer. What say ye all?
My 2.3L Mazda 3 got worse mileage on GC as well. I went from 27-28mpg down to 25-26mpg... and all I was doing at the time was solid freeway driving! Tires were always kept at 38psi and the driving conditions didn't change.

I'm now using M1 5w20 and it solved the problem nicely
> M.P.G. difference between 30 wts? please.

Next to none or immaterial. There are other differences that you will encounter in driving that will make a difference, the viscosity difference between 30 weight oils will not make a material difference on fuel consumption, despite what some claim.

My own personal evidence has shown a negligible difference going from GC 0W30 to a conventional 20W50 in a small four cylinder motor...and that is a very wide range of viscosity.


MPG is huge right now. The prices at the pump are scyrocketing every couple of months. This mpg loss is an issue that is apparent in some applications. Some person hears all of you praise this oil like it's the best thing ever invented and throws it in his/hers new 06 civic. In this application it is well beyond the recommended 5w20 spec and in completely unnecessary. PEOPLE DON'T REALIZE THAT that any synthetic oil will protect almost exacly the same. So when someone tries this THICK GC in their civic they could possibly have a drop in MPG. Especially in a cold winter climate.

MPG is huge right now.

This issue apparently evaporates when people buy a new vehicle. FWIW I can realize a 12mpg difference with just driving style and season. Summer @ 50mph = 50mpg, winter @ 75 mph = 38 mpg; same 5-20 oil.

I think people need to slow down if they want to conserve gas, not blame it on a 30 weight oil.
>>> Out of curiousity, does Oregon change their fuel in the winter to oxygenated fuels? This may also have an effect.

My GC was run during the summer

I think the mpg thing mainly depends on your vehicle. Some vehicles seem to be pretty much unaffected by thicker/thinner oils in regards to mpg... while others tend to be much more sensitive. My 2.3L Mazda 3 is spec'd for 5w20 oil from the factory, and I also know that this particular engine was pretty much built around using 20 weights. I'd say that's why I notice the MPG difference, while people who drive vehicles not spec'd for 5w20 notice little to no difference.

Just my .02
if you think you pay alot for gas. my sister is stationed over in italy with her husband. they pay over $7 a liter for gas. now you still think over $2 a gal is alot now? I know she said when she comes back to the states she will be the only person that will think $2 a gal is cheap

I could see you complaining about a drop in mileage if it was like a drop of 10 MPG. but gripe about 1 to 2 MPG thats a lil anal in my book.
Here we go again. Now your milage may differ.

I have two 1.8 1ZZ-FE engines in idential syle 2000 Chevrolet Prizm cars. Currenlty, one has 104K and the other just turned 60K this week. The 104K engine is on its second run of GC. The 60K engine finished Auto-RX treatment in Nov. and then had left over M1 5w30 put into it (currently at 2500 miles). No difference in mpg between the two. Same driver, same low desert sea level conditions, same MPG of 32-34 mpg. Like I said, your milage may differ.

It will be interesting to see if the MPG effects the 60K car on the next oil change. I didn't know about CG until October and it is used in the 104K engine with no hit in MPG. The 104K engine has never had a Auto-RX treatment and has been on M1 since purchase at around 55K .... that is until the change to CG in October.
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