Have been running GC 0W-30 in the winter. I know it's not that harsh here but I regularly travel into the mountains where it's a bit colder. No such issue in the summer but we regularly get days that are 110-115 so I want something not quite as thin as the GC. Here is Las Vegas, NV.

I have an AMSOIL membership so I was eyeing the "European" formula 5w-40. Thoughts on this oil? Other 5W-40 or 10W-40 suggestions?

 

OK 50 views well here is how it went down. In my searching I found mentions that the European and/or Australian/NZ manual states that ambient temps over 59 F using 20w50 is called for. Read that the reason this is not in the US manual is due to varying EPA regulations. Apparently someone posted pics of the non-US manual as proof though all the links were broken now. I took the absence of anyone calling it BS as meaning it was real and went with the 20w50 from AMSOIL.

First impressions:
Engine much smoother and quieter over 3K RPM.

No more drip from plug. GC0W30 was my first oil change, there was no washer on the plug so I didn't know there was supposed to be one until I started noticing the drip spots which seemed to be originating from the plug. Sadly I totally spaced buying the washer until after I took the plug out and drained it the second time. I went to autozone in the middle of it and apparently all their washers were recalled, so I just put plug in washer free. No dripping thanks to thicker oil. On my way to stealership today to get washers for next time.

 

Just a side note: An unintended consequence of this seems to be a reduction in fuel economy (which I expected though not this much). Normally I will be around 400 when the gas light comes on. With this new oil I reached that point @ 340 miles. I am 99% sure the oil is the reason why, though I haven't checked codes, the timing is just too convenient.

I'm gonna try through with another tank of gas and if I get the same result then I might bite the bullet and drain it sooner than later. Hard to justify losing 60 miles a tank.

 

Probably doesn't burn as good as the other oil when sucked int your IM

 

Would there be any workaround for that?

 

5W/30 winter, 10W30 summer.

Why on earth would you jump from 0W-30 to 20W-50. You dont need 0W-30 unless the ambient temp is in the 20s. In AZ I could see 20W-50 in the heat, but 10W-40 would be better.

 

By mountains I mean Utah, North Nevada, California, that's in the winter... for snowboarding. Temps in those places are well known. 0W-30 is called for. I live in Las Vegas. It is 102 right now and we aren't at the hottest part of the day or year yet. 20W-50 is ok.

Anyway I still finished my first tank of gas at 22mpg which is within range if I did more city driving. This next one I am back to what I usually get so I am no longer worried about it. I will change at 6000 miles and get a UOA.

So basically in the summer I need protection from 110+ heat. In winter I need something that will be thin after the car has been sitting overnight in Rocky Mountain winter environment. I know it's weird but it makes sense when you think about it.

 

Once warm, all three of those oils are the same viscosity.

 

Any decent synthetic will do that...in any viscosity.

The bearing clearance doesn't change due to outside temperature.....and the engine temp doesn't change due to outside temp.

 

Not saying it's a huge one but there has to be some difference in 115 vs 20 even after the engine is warmed up.

I was under the impression there were established outside temperature ranges per viscosity as seen on this chart.

 

That might be a general guideline, but it doesn't take engine design and type of oil into account. Your owners manual probably recommends 5w-30 regardless of ambient temperature. Many manufacturers specify 5w-20 or 0w-20 in their engines today as the engines are designed for the lighter, more efficient oils.

Also, as stated in another reply, above, a good synthetic will provide an extra margin of safety against breakdown in Las Vegas heat. AMSOIL 20w-50 is a fantastic oil, but I wouldn't recommend it for your application. AMSOIL 5w-30, 10w-30 or even 0w-30 would be a better match for your engine and they're designed to excel in severe operating conditions such as yours.

 

Great post and that would have been the case but in searching I heard mentions that one of the foreign manuals called for 10W40 or 20W50.

Initially when I posted nobody responded so I decided to just take the plunge this time and if anything went wrong I could always change out the oil easily enough.

I just went searching for the thread I read it on, couldn't find it but I found something better. A33Black also runs 20W-50. He posted this picture which is reputed to be from the European version of the A33/Cefiro manual. I read speculation that the 5W-30 guideline is due to the EPA and not in order to achieve maximum performance/protection.



This is the thread I found it in.

 

The oil you are using will definitely work, but its not the best match for your engine. Even the European manual you posted refers to the 30-weights as being "preferable" and the thicker oil as being "suitable" in hot environments. And keep in mind these manuals are written with the assumption that one is using petroleum oil that meets minimum performance standards...these oils will shear back out of their stated viscosity range when subjected to high temperature/high stress conditions...so the specified 50-weight one puts in the engine might end up providing the film thickness of a 40 weight or 30 weight after a few thousand miles of hard use (and at the same time thicken when its cold, causing increased wear and lower fuel economy during warm-up). A premium synthetic 5w/10w-30 such as AMSOIL ASL or ATM will maintain its viscosity in these extreme conditions and provide overall greater efficiency.

Vegas is probably hotter than where we're at in San Antonio, but it still gets pretty hot down here in south TX. My 4th gen is pushing 200K and it has run on AMSOIL 0w-30 for the last 12 years or so...prior to that I used AMSOIL 5w-30. The engine is quieter than many new cars and Zero oil consumption between extended drains, even today. Ran my '00 Infiniti on the same oil until I sold it couple years back...same results. Customer with nearly 350K on a Sentra till a road hazard did it in..he drives about 40K/year and now he's driving a Corolla with 170K on the clock...same oil, great longevity from the engines. Just pulled a fully loaded u-haul over 300 mi with my Frontier...close to 3000 pounds....AMSOIL 5w-30, 10K on the current oil, 100+ deg ambient temp and it hasn't used a drop of oil.

Bottom line though is that you have to do what you are comfortable with. If you feel more comfortable using the thicker oil, go for it...

 

Well to be honest this is only my second oil change and I am set on using better oil than I used in my 4th gens so I am still trying to figure out what I am comfortable with. The keywords they use "preferable" and "suitable" do seem to be good indicators so perhaps you are right. It just seems weird they would even mention 20W-50 at all if 10W-30 was best no matter what, especially in Europe, outside of Greece or maybe southern Spain I don't know where it possibly could approach Las Vegas like temps consistently.

Would a UOA actually be able to tell if this oil worked well for me?

 

A UOA will show wear metals, properties of the oil (viscosity, TBN, etc.) and contaminants such as water, fuel or glycol. I would expect AMSOIL 20w-50 to remain in grade and show below average wear metals, so I'm not really sure if there would be benefit in spending the money on an analysis. Wouldn't hurt to do one, however, if you just wanted to see how the engine was doing...

 

and stop driving until you see the gas light, you'll ruin yor injectors soon...

 

Could you explain that please?

 

That foreign book may be intended for an area where oil selection is pretty limited. Possibly they are just listing "acceptable" oils?

 

I put some 10W30 Mobile 1 Synth in the Mustang, mostly because I had it lying around and secondly because its so hot lately. In about 4-5k miles I'll put in 5w20/30.