How important is multi-grade oil for hot countries?

[sagaboy]

How important is multi-grade oil to cars owners in hot and humid tropical countries (85F day/78F night)? When it won't even takes 10 minutes for the oil to reach 180 F operating temperature – seems to be that the oil companies are taking everyone for a ride where I live.

Currently, we have M1 pushing their Gold O/40wt and Castrol’s synthetic going one-up with their 10/60wt, Shell synthetic 15/50wt cleans better and BP synthetic 5/40wt clean 30% more than the best for those who can claim lower or higher they claim clean better, etc.

Admittedly, when I was using dino straight 40wt HD oil on my 40 year old bug engine it took 45 seconds for it idle steadily (without using the choke), 25 seconds when I switch to 20/50 wt and only 10 seconds when 75/90wt transmission oil was used. I have not yet tried synthetic oil on my old engine

 

[mdocod]

You'd be fine with a straight-weight oil (none-W rated)... just so happens, that most of the really good oils out there, have a W rating... So it doesn't matter too much. Having the W rating, even in hot climates, will still result in better pumpability when you first start your engine.

As for what weight to choose- I think that depends on the engines needs..

 

[oilyriser]

How's the gas quality there? Is there any low octane stuff sold, that might generate a lot of knock?

 

[andyd]

75-90 gear oil in a Bug??????????? I would stick to straight weight motor oil. I use to run 30w in mine, but in your climate maybe 50w or 20w 50 certainly not anything with a cold rating less than 10

 

[TallPaul]

IIRC most gear oil will destroy the bearings in an engine because of the high sulfer. Redline gear oil may be the exception.

Go with a good synthetic (i.e, one that has few if any viscosity index improvers so it is like a straight weight) 10w40.

 

[farrarfan1]

quote:

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Originally posted by sagaboy:
How important is multi-grade oil to cars owners in hot and humid tropical countries (85F day/78F night)?

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What's so extreme about this? Any decent 5W3 or 10W30 should handle this. Works well enough in areas of this country that are warmer than this.

 

[j m z]

I think 10w30 is still ok, for better protection use 10w40. That's what I do here to my 2005 CR-V 2.4L and 2004 Isuzu 2.5L turbo diesel..

 

[Eddie]

Sounds like my normal temperatures here in SW Florida. Nothing special required for those temps. My owners manual says 5w30 to 100F. and 10w30 if temps frequently go over 100F. You should use what your owners manual recomends and that first 10 minutes is where the most wear occures. Remember that an engine at normal running temp is ~ 200F so a 75F start up IS a cold engine.

 

[pitzel]

Nothing on the shelves here in San Jose, CR, less than a 25W-50 weight, with the exception of a few dusty SAE 40 bottles found in the occasional bomba.

High mileage motor oil is 25W-60. Castrol has begun to market their High Mileage brand here.

 

[mechtech]

I wouldn't use a straight weight oil.
You still want start up pumpability.
A new 10-30 would be great, and not break down easily.

 

[sagaboy]

We only get quality premium 92 RON unleaded gas here for $1.50 per gal

and $1.66 for Shell V-power.


That’s right, it is for the transmission, anyway the manual recommended 90wt but it was written 40 years ago; I don’t use it for the engine oil

 

[Trex101]

Why would you choose straight 40wt when you can get delo 15w40 for around rm$60?

 

[sagaboy]

You are right, there is no reason to use straight weight but Rm60 ($16.20) for 4 liters 15w40 is way to expensive, I could buy them directly from the dealer; $6.70 for 4 liters Castro dino 15/40wt or 20/50wt but I usually buy them for $3.20 per 4 liters from my friendly office next door mechanic 50 gallon drum.

 

[TallPaul]

A straight weight in 85 F temperatures probably will be a whole lot thinner than a 5w30 at zero F. I don't see any problem to a straight weight in his climate.

 

[sagaboy]

How do you explain this: "...when I was using dino straight 40wt HD oil on my 40 year old bug engine it took 45 seconds for it idle steadily (without using the choke), 25 seconds when I switch to 20/50 wt..."

Anyway straight weight HDEO available in my country is for diesel engines and nothing much is indicated on the packing other than detergent “Heavy Duty Oil for diesel”, no API standard, maybe a “super” advert added here and there, etc. but they are sold pretty cheap at $3.8 per 4 liters. Would these type of HDEO suitable for my air cool engine?

 

[sagaboy]

True in your case but where I live we don't get "what you call that"--wind chill factor therefore even when the car sit overnight the engine stay warm.