Why use a different weight than manual says?

[HTSS_TR]

Originally Posted By: Audi Junkie
I also have a problem with a synthetic recommendation in a non-turbo car. Like the VW 2.0. Used to call for any 10w30, but later went to extended drains and a VW 502 spec oil. That's what the synthetic is for in non-turbos, extended drains, which not everyone does, and imo, more changes of conventional oil do a better job anyway.

Another thing is the Euro spec 5w-40. It is just not necessary in North America driving with a stock engine. We just don't generate the oil temps necessary to thin the oil down to the 9cSt "danger zone". I did a quick calculation of a driver who used oil analysised his BMW oil. At his track oil temps, the BMW oil thinned down from 12 to 9cSt, and the used oil analysis was fine. Another driver who barely break +100c can run 5w30 or even 5w-20 in some circumstances.

I have Havoline 5w-20 in my Mom's VW 2.0 with no worries at all.


I have xW20 instead of Mobil 1 0W40 in '00 E430, the engine is much quieter at all RPM with thinner oil. The reason I have xW20 in this car the last 2 years is it rarely been driven more than 15-20 miles trips.

It doesn't have oil temperature gauge, but my guess is with the short driving distances the oil temp is mostly under 80-90C. If this car never see oil temp above 120-130C why does it need thicker oil ?

 

[21Rouge]

Originally Posted By: Warstud
Now if you look at the manual you will probably see at least three different grades of oil for your vehicle based on outside temperature.


Originally Posted By: 21Rouge
Not for the two cars I have i.e. both are GMs and the manuals for both specify only 5W30 and barely permit 0W30 (only if the temperature falls below -20F).


Originally Posted By: Warstud
That's something new to me. Are these newer cars? Hard to believe you can only run a 0w30 below -20F. Maybe they know something we dont.

Originally Posted By: 21Rouge
I wasn't clear. You can use 5W30 for any temperature but have the option of using 0W30 if the ambient temperature is below -20F. No other grade of oil is permitted according to the manual.

And these instructions are the same for our 05 Pontiac and 09 Chevrolet.


Originally Posted By: Gary Allan
Most have those arrows/bars of suitability on a temp chart.

I can only imagine the 0w30 extending beyond on where it begins compared to where the others do. The "finish line" should be the same.

I could see it saying "where temps are at or below -20F, a 0w30 is suitable for use".

That in no way prohibits its use 24/7/365. That's not how that's to be interpreted.


Gary of course your interpretation should be de facto as of course we all know that a 5W30 can it be replaced by a 0W30 but I am confident that this is not permitted according to the manual. The only oil shown next to that traditional thermometer is a 5W30. The manual is reasonably clear that a 0W30 is permitted only in extreme cold.

 

[Garak]

Originally Posted By: 21Rouge
Gary of course your interpretation should be de facto as of course we all know that a 5W30 can it be replaced by a 0W30 but I am confident that this is not permitted according to the manual. The only oil shown next to that traditional thermometer is a 5W30. The manual is reasonably clear that a 0W30 is permitted only in extreme cold.


Just about all oils I can think of in a 0w30 are synthetics. They're not as sensitive to extremes in temperature. They'll hold their viscosity as a 30 weight with no problem. GC 0w30 is thicker than most, yet, closer to a 40 weight, as many others have pointed out here.

My Audi manual says it best. Don't "panic" (yes, they used the word panic) about ambient temperature fluctuations. We had +20 C the other day, and then a snow storm a few days later. I didn't panic and change all my oils back to 5w30 for fear of cold starts.

 

[HM12460]

My owners manual calls for 5W-20, so thats what i use and am quite content with it.

 

[Garak]

Originally Posted By: HM12460
My owners manual calls for 5W-20, so thats what i use and am quite content with it.


Good point. Some vehicles, however, have and still do have more than one recommendation. Sometimes it's worth experimenting a bit.

My Audi recommends the heaviest oil possible for the temperature conditions. They recommend even 20w-50 in the summer, if I so desire. I don't always drive enough to warrant putting 20w-50 in for the summer and then have to do an unscheduled change when the temperature dips. Our summers are too short. So, 5w-40 HDEO works fine all year.

5w-20 is fine oil. There are few engines, however, that would likely suffer a catastrophic or premature failure from using something slightly thicker. As an aside, far too vehicles are equipped with oil temperature gauges.

 

[river_rat]

Originally Posted By: ThirdeYe
My cap never came with a recommendation on it. It just says "Honda: Oil" on it.

Mine just says 710...now how would a fella even know to put OIL in there?

Originally Posted By: Garak
5w-20 is fine oil. There are few engines, however, that would likely suffer a catastrophic or premature failure from using something slightly thicker. As an aside, far too vehicles are equipped with oil temperature gauges.

Yup. And it's important not to lose sight of the fact that average 20 wt is a lot more than 2/3 as "thick" as 30 wt.
...and many brands almost overlap between 20 and 30 viscosity. I think the big jump in 20 to 30 in the label numbers play mind games with buyers.

 

[ericthepig]

I've owned my '98 Sienna since late 2001 (1MZ-FE). Found out about the sludge issue shortly thereafter - researched the web and found several folks claiming short OCIs on dino that ended in sludge. Meanwhile Toyota mechs on BITOG have stated they never saw a sludged 1MZ-FE on short dino OCIs.

 

[kcfx4]

Originally Posted By: FL_Rob
Some manufacturers recommend oils based on CAFE standards,not longevity,thats not good enough for me.My owners manual actually says 'use of synthetic oils are not recommended'..................WHAT?,Okay..THATS what I'm gonna do..

If I remember correct, Mazda does not recommend synthetic, I believe it even voids the warranty if used in their Rotary engine.

 

[Warstud]

Originally Posted By: river_rat

Mine just says 710...now how would a fella even know to put OIL in there?


Didn't realize there's so many oil caps not labeled. All the more reason to change your own oil and not take it to Iffy Lube.

 

[river_rat]

Iffy Lube? Never! Besides I like changing oil...

(It's actually labeled, I just couln't figure out how to write 5W-20 upside down.)

 

[hardcore302]

Lol iffy lube

 

[Scotty1981]

Originally Posted By: Warstud
How many people go by the manual anyway? I think most of us use what is labeled on the oil cap. For my truck it recommends 5w30 but I'm using 10w30 in it now because it's warm outside and was the only grade they had on sale. Now if you look at the manual you will probably see at least three different grades of oil for your vehicle based on outside temperature. The one on the oil cap is probably the best mineral oil for all seasons though.


I generally use the reccomendation in the manual for my oil and coolant and some of the more important things, as far as windsheild washer fluid and door seal conditioners and what not though I don't think it matters too much.

 

[ahoier]

As someone posted earlier.....a lot of times the Owner's Manual will be extremely lax....

In my 07 Kia Rio, the oil fill cap had 5W-20 printed on the cap.

In my 08 Kia Optima, the oil fill cap had 5w30 printed on the cap.

BUT, both Owner's manuals had a "temperature chart" of what oil to use if in certain temperatures....all I could find on my HDD is the Rio page, and yea, here it is

The Optima had a lot more "allowance" even up to 15w40 I think I recall.....

So basically, it "specs" 5-20 as per the oil cap, - BUT, could also use 10-30, 5-20, or 5-30. As long as it met the ILSAC GF-3 or above, and the API Service SJ, SL, or above.


Something I've heard though about those Owner Manuals, they "share" the manuals between makes/models.....which is why they contain 5 different "stereo" set ups, and all these "If APPLICABLE" features listed throughout the book, they make the manuals extremely "broad" to apply to all/most vehicles in their "line"....then all they have to do is create a new "cover" to the book, with the "right" vehicle model, etc....and it makes it easier and cheaper to mass-produce their owner's manuals...

That's why I've always used the owner's manual with a grain of salt It's good for reference, but that's about it, better off checking under the hood to see what the fluids are "speced" for too....and consult the manual for a second opinion.

Another example, both my manuals reference a "Replace Fuel Filter" maintenance item....yet NEITHER of my vehicles contained "serviceable" fuel filters.....but apparantly, somewhere down (or up....? previous year models did lol) the line they did And they just didn't "update" the manual/service schedule....

 

[castamir]

Many ULEV cars require 0w20 or 5w20 cars not only to meet emission requirements, but they are designed to use such oil. The Mazda3 utilizes 5w20 conventional oils, and the guys on the Mazda3 forums have proven with UOA that their engines are in outstanding wearing condition even when using such light oil in racing conditions.

To be honest, factory recommended weight oil may not be absolutely superior in every single condition, but they are both practical and safe for a wide variety of operating conditions.

Most people prefer using the heavier weight European formula oils in their econo boxes. Although that is completely fine for the engine, these people are not gaining much protection for the large sacrifice in fuel efficiency and horsepower. Likewise, many race teams shy from using the ultra-heavy weight Castrol Synthetic 20w60 engine oil even that is what BMW suggests for the M cars.

 

[Garak]

Originally Posted By: river_rat
Yup. And it's important not to lose sight of the fact that average 20 wt is a lot more than 2/3 as "thick" as 30 wt.
...and many brands almost overlap between 20 and 30 viscosity. I think the big jump in 20 to 30 in the label numbers play mind games with buyers.


Quite right. Even given the proliferation of 5w-20, and the relatively safety of following the manufacturer's instructions, I would say there aren't a lot of engines out there that absolutely must run 5w-20 all the time, in all weather conditions and all driving conditions.

It will likely do the job almost every time, but that doesn't mean it's always the optimal choice.

 

[Audi Junkie]

The problem with a blanket recommendation, like "SL" is that the ~other than~ 30 weights don't really have to pass as tough of a sequence for the spec. That is, you run a 10w-40 as hard as you run a 10w30, you may run into problems.

 

[kcfx4]

for whatever reason, some ppl think theyre smarter than the engineers that designed/tested the engine, down to the chemical engineer at the oil company. in fact, if you read majority of the posts on here, you might think companies are just plain stupid for still making 10w anything. as for me, i use my gut alot to make certain decisions...but my gut is in no way smarter than the engineers paid good money for R&D amongst other reasons a certain oil type is recommended for a specific engine. certinally not when it could come down to the life expectancy of an investment.

 

[Bigsyke]

What about shearing and/or loose tolorences as the engine ages, when using an engine that uses an oil pressure drivin' timing tensioner? Say the engine calls for a 5w30, but due to drivetrain shock with a higher clamping pressure plate, wouldnt upping to a 5w40 such as T6 make more sense?

 

[kcfx4]

i would assume the engineers take that example amongst many others in making their recommendations. and just my opinion here, but maybe more frequent than 10k oci's could save ALOT of money in the long run

 

[Garak]

Originally Posted By: kcfx4
for whatever reason, some ppl think theyre smarter than the engineers that designed/tested the engine, down to the chemical engineer at the oil company.


Perhaps people wouldn't think they're smarter than the engineers if the engineers actually had the freedom to make their recommendations without being vetted by their marketing people and CAFE. We have too many different specs for the same engine and vehicle in different markets. We've seen oil caps and automotive manuals contradict each other. I'd also like to know how many of the engineers actually believe that 5w-20, for instance, is the perfect oil for engine X under all circumstances and conditions.

As for engineers, you're looking at American and Canadian engineers who have to live within CAFE's guidelines. German cars seem to have no problem with a variety of viscosities for one engine. I'm sure these recommendations were made in consultation with engineers, just in a country that falls outside of CAFE's de facto jurisdiction.

There's nothing wrong with 5w-20. It is not, however, a miracle oil. It's there, for the most part, to satisfy CAFE regulations, just as 5w30 was before it.