engine oil viscosity

[zeng]

Originally Posted By: zeng
SAE paper(s) did suggest that majority of engine wear is corrosion wear, especially at startup and warmup phase or 'short' period after fully warm up phase.
They are influenced by among others cold oil (and ambient) temperaturess, some (or all) biofuels , fuels additive and engine oil additive packages, driving patterns etc.

However, with improved quality of current day fuels/oils and in relations to (localised) adhesion and abrasion wear,
I'm personally not quite worried about corrossion wear (which constitutes majority of engine wear) for the following reasons, namely:
a) they are not localised generally; and
b) where localised corrossion wear does occur , they are not at the contacting surfaces ; and
c) where corrosion wear occurs and localise at a certain pair of contacting surfaces (which I'm highly doubtful of ), it's likely spread out along the surface profiles of contacting components ........
such that all 3 scenarios above are not likely to result in changes in (measurable) components dimensions (in microns or a fraction of a thousandths of an inch) ---
hence, its (meaning corrosion wear) effect on reduction of engine components longevity is insignificant AND inconsequential , if any.

This quote is in referrence to the other thread claiming TGMO 0W20 as having 'lower' metal wear # vis-a-vis Mobil 1 0W40 as truth (which I forego contesting, for now).

 

[demarpaint]

Originally Posted By: hamm
but thinner oil means more wear specially in a hot temp , air con and traffic ... right ?


Zeng summed it up nicely. It doesn't equate directly to more wear. But the 30 grade oil for example will provide a better margin of safety if your engine suffers from fuel dilution, or if something should go wrong with the cooling system, or some other event causing the engine to run hotter than it normally would. So given a choice in extreme heat I'd run a 30 grade oil over a 20 grade.

 

[Gokhan]

Also, if you use 0W-30, 5W-30, or 10W-30, make sure that it's ACEA A1/B! or A5/B5, not A3/B3 or A3/B4. The latter are too thick for this low-powered, nonturbo application and will rob off fuel economy and horsepower, making your engine sluggish.

In summary use A1/B1 or A5/B5. The latter is slightly better. Do not use A3/B3 or A3/B4.

 

[FCD]

Originally Posted By: Gokhan
Also, if you use 0W-30, 5W-30, or 10W-30, make sure that it's ACEA A1/B! or A5/B5, not A3/B3 or A3/B4. The latter are too thick for this low-powered, nonturbo application and will rob off fuel economy and horsepower, making your engine sluggish.

In summary use A1/B1 or A5/B5. The latter is slightly better. Do not use A3/B3 or A3/B4.

20W-50 will make his engine sluggish, a A3/B4 30 grade certainly will not.

 

[zeng]

Originally Posted By: hamm
hey i have a 2016 Mitsubishi lancer 1.6L as you can see in the pic the owner manual says choose engine oil according to atmospheric temperature.
the temperature where i live is between 18-35 Celsius ( 63-97 fahrenheit )

the oil station told me to use 10w40.

the dealer says 20w50

i dont know what viscosity to choose . thank you so much

In my ambients of 24*C to 33*C, most dealers use xW40 and rarely 10W30.
20W50 are always recommended for cars with oil consumption issue ........ and in older cars

 

[Nissan101]

Sigh.....why would you all say 20w50 is too thick for this car when the manual clearly recommends it(as well as the dealer).

 

[Fastcompany]

20w50 is too thick for startup. Not to mention until the oil is at full operating temp your oil pressure relief valve is going to hang wide open and probably still over pressure the system. My vote would be for 5w40. Good start up viscosity the oil pump will easily pick it up and it will have good protection in higher heat. I've never seen an o.e. chart that is that broad.....20w-50 to 0w-20 lol. Once upon a time internal engine clearances played a roll on oil viscosity not just what temperature it is out.

 

[FCD]

Originally Posted By: Nissan101
Sigh.....why would you all say 20w50 is too thick for this car when the manual clearly recommends it(as well as the dealer).

I can't see any advantage to using it over a Full synthetic 5W-30 or 5W-40, it would only increase fuel consumption and eat up horsepower.

 

[FCD]

Originally Posted By: Fastcompany
20w50 is too thick for startup. Not to mention until the oil is at full operating temp your oil pressure relief valve is going to hang wide open and probably still over pressure the system. My vote would be for 5w40. Good start up viscosity the oil pump will easily pick it up and it will have good protection in higher heat. I've never seen an o.e. chart that is that broad.....20w-50 to 0w-20 lol. Once upon a time internal engine clearances played a roll on oil viscosity not just what temperature it is out.

The chart on my Ford Capri's owner's manual allows anything between 5W-20 to 20W-60 depending on ambient temperature.

 

[Gokhan]

It looks like 20W-50 is one-size-fits-all oil in some countries. It's sort of like some fleets using 15W-40 in every vehicle in USA.

 

[FCD]

It definetly is widely used in South America, the middle east, Africa, Southeast Asia, Australia ( although not so much anymore ), and in Spain i have no problem finding it.

 

[zeng]

Originally Posted By: FordCapriDriver
Originally Posted By: Nissan101
Sigh.....why would you all say 20w50 is too thick for this car when the manual clearly recommends it(as well as the dealer).

I can't see any advantage to using it over a Full synthetic 5W-30 or 5W-40, it would only increase fuel consumption and eat up horsepower.

How so in typical everyday driving ...... when engine power curve and mechanical efficiency curve are NOT of similar shape and they cross path ??
Yes,post very cold start in winter thicker oil may contribute higher drag losses,if measurable.Period.