5wx30 oil confusion

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edwardh1

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in another topic, people posted what their car manuals said about what oil weight to use (many in foreign countries)
many seemed to say dont use 5wx30 over 60 degrees F.
whats that about? my 99 nissan says ok all the way up to 100 F.

did I read all those links wrong?
 
Over 60F? Come on. I ran a 5w30 synthetic in a tracked car on a 120F day and my oil temps hovered around 105C. (Car did have an oil cooler oem)

I have no concerns about 5w30 if that is what your car is specd for.

Jeff
 
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Could be any number of things. If they call for 10W-30 at higher temps, it could be because the engine was designed/manual written when conventional motor oils were less shear stable, so 10W-30 provided better protection against shear. If a xW-40 is called for at higher temps, it is to ensure that hot viscosity is thick enough (before engine cooling systems were as efficient as modern ones). Some manuals call for anything from a 5W-30 to a 20W-50 for the same engine, depending on ambient temps. Some of it could also be the sales market (Aussies like their oils nice and thick, middle easterners will see much higher temps than anyone in NA, etc.).
 
Seems like manufacturers change the owners manual oil recommendations to suit the countries/areas that the cars are sold in. IMO oil weight (within reason) takes a 2nd seat to maintenance.
 
Originally Posted By: BobsArmory
Seems like manufacturers change the owners manual oil recommendations to suit the countries/areas that the cars are sold in. IMO oil weight (within reason) takes a 2nd seat to maintenance.


This is correct, my Toyota Corolla 2zrfe 2009 model owners manual recommends basically any oil grade from 0w-20 to 20w-50.
Below -29C 5w-xx or 0w-xx above -7C anything including 20w-50.
Toyota head offIce sell Mobil 2000 10w-40.
 
One big reason is CAFE. Other countries don't have to mess with it so much. The USA has no choice. Before I get bashed, I'm not saying lighter oils will not work. I am saying it's all about fuel economy .
 
Some oils are now "back specked" for older Toyota engines. I take it all with a grain of salt when it comes to oil weight.

My Toyota Owners manual calls for 10w or 5w-30 in my 3rd generation V6 T4R. The oil cap on my vehicle has 5w-30 as the appropriate grade. Toyota, according to their TSB, has back specked my 1997 vehicle for 5w-20.

If I look for help with my oil on the Mobil 1 site, they recommend 10w-30. However, it is appropriate to use 5w-30 or 0w-30 according to the Mobil 1 site.

I run what I find on special and if it thick, I thin it out with a lower grade oil. Case in point.....I picked up Mobil 1, 15w50 on clearance for $2 a quart. I ran 4 quarts of Mobil 1 5w-20 and 2 quarts of the clearance 15w-50 in a blended mix. No problems and it went through last winter like a champ.
 
Originally Posted By: Jeffs2006EvoIX
Over 60F? Come on. I ran a 5w30 synthetic in a tracked car on a 120F day and my oil temps hovered around 105C. (Car did have an oil cooler oem)

I have no concerns about 5w30 if that is what your car is specd for.

Jeff


They call it "thick oil logic". As soon as it hits 60F you gotta dump 40 or 50 in that speced 20 or 30 car baby! It gives you "protection" from the "heat"!
 
Originally Posted By: Doc Holiday
One big reason is CAFE. Other countries don't have to mess with it so much. The USA has no choice. Before I get bashed, I'm not saying lighter oils will not work. I am saying it's all about fuel economy .


I totally agree.
 
yes I thought mayve the engines were built differently for different countries but I think main engine rod and bearing clearances are still what they were 20 years ago? like ,0015 or so??
 
Originally Posted By: Doc Holiday
One big reason is CAFE. Other countries don't have to mess with it so much. The USA has no choice. Before I get bashed, I'm not saying lighter oils will not work. I am saying it's all about fuel economy .


This.
 
Originally Posted By: Doc Holiday
One big reason is CAFE. Other countries don't have to mess with it so much.

I won't bash you, but there's a little more to it than that. If a vehicle is "best served" by a 30 grade, there's not a lot of point in running SAE 30 in the summer, 10w-30 in the spring and fall, and 5w-30 or 0w-30 in the winter, assuming that all work about the same at operating temperatures and that all are able to handle a reasonable OCI.

The elimination of seasonal OCIs is right up there with the full flow oil filter with respect to maintenance improvements in automotive history.
 
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