5W-10W30/40 or 15W40?

[GerardC]

Most vehicles call for 5-10W 30 or 40. Can you substitute with a 15W-40 safely? Would clearance be a problem; i.e. bearings etc. Thanks. G

 

[jayhawkRoy]

I generally go with the manufacturer's recommendation for the temperature range in your area. I would not use 15W-40 in any new car. I might use it in an old car that might have ring problems, although 10W-40 would work in about the same fashion. Best I can do. /forums/images/graemlins/smile.gif

 

[Junkman]

Most manufacturers must make a generalized recommendation and leave it at that. Clean oil is more important than the weight. The correct weight oil that is contaminated by products of combustion is worse for the engine than a different weight oil that is clean. Pick you demons, but keep clean oil in your crankcase and you will have less demons to be concerned abut... /forums/images/graemlins/grin.gif

 

[slowrev]

I would use what the manufacturer recommends especially for the bottom number. Some cam bearing clearances are so tight that the thicker when cold oil might not flow in there as well as it should. Once you get a lot of miles and out of warranty then maybe go to the thicker oil.

Synthetic is good oil to use especially if you plan on keeping the car for a long time. If trading in 3 years or so good grade of standard oil is fine.

 

[cp1969]

I had a Toyota Corolla that had an oil temperature gage. At one point I decided the oil pressure was lower than I liked and substituted 20w-50 for the 10w-30 or 10w-40 I was running. The oil pressure came up all right, but the oil temperature increased more than I was comfortable with so I went back to the lighter oil.

 

[familyman]

The main reason we have lighter oils these days is this; auto manufacturers need to hit their fleet EPA mileage numbers, and lighter oils yield slightly better mileage in any vehicle. I'm sure you noticed when 5W30 oils appeared a few years ago, and thought it strange just as I did. Heavier oils, ie 15W40, 20W50, etc., generally provide a "cushion" for motor parts with the only downside being minutely reduced mpg and slower flow until warmed up. I generally change oil weight to match the season: 15W40 for April thru October, 10W30 for November thru March. I use synthetic oil year-round (after the engine is broken in, of course). Yes, your engine can run 15W40, especially in warm weather. Oil passage dimensions and bearing clearances are not a problem. My 2003 Toyota Tundra has been treated to this regimen and runs beautifully. Any oil that meets the manufacturers service spec will support your warranty.

Charley

 

[Bird]

</font><font color="blue" class="small">( The main reason we have lighter oils these days is this; auto manufacturers need to hit their fleet EPA mileage numbers, and lighter oils yield slightly better mileage in any vehicle. )</font>

That was my understanding, too, but in recent years I've also heard (don't know it for a fact) that closer tolerances, smaller channels for the oil to flow through, etc. have required lighter oils. So, at least since '99, my Fords have manuals that specify 5W-20 oil. I was also told by the owner of one of the quick oil change places that the State Department of Public Safety was told that the use of a heavier weight oil would void the warranty on the highway patrol cars, even in the Texas heat. I have not tried to verify either of those things, but I'm using the 5W-20 as recommended in the manual.

 

[TresCrows]

</font><font color="blue" class="small">( The main reason we have lighter oils these days is this; auto manufacturers need to hit their fleet EPA mileage numbers, and lighter oils yield slightly better mileage in any vehicle. I'm sure you noticed when 5W30 oils appeared a few years ago, and thought it strange just as I did. Heavier oils, ie 15W40, 20W50, etc., generally provide a "cushion" for motor parts with the only downside being minutely reduced mpg and slower flow until warmed up. I generally change oil weight to match the season: 15W40 for April thru October, 10W30 for November thru March. I use synthetic oil year-round (after the engine is broken in, of course). Yes, your engine can run 15W40, especially in warm weather. Oil passage dimensions and bearing clearances are not a problem. My 2003 Toyota Tundra has been treated to this regimen and runs beautifully. Any oil that meets the manufacturers service spec will support your warranty.

Charley )</font>


It's EPA and fleet gas mileage and nothing more. Improoved materails and design allow the engines to take the abuse such thin oils dish out.

Uh, oh, you talking Toyota and Tundra----quietly slipping out of room and closeing door behind me--------J

 

[familyman]

Sounds like you agree, except for the Tundra part. O.K., I'll bite; did you have problems with a Tundra or other Toyota? I'm completely satisfied with the truck except for heavy towing -- she does get tossed around a bit. I'm considering trading up if I can find a good deal, maybe even a diesel.

 

[Henro]

I can't point you at the previous thead, but I remember someone emailing Kubota and asking about their 5w-40 spec for tractor engines...and the reply was use 15w-40 as that is commonly available and they just had not got around to up dating thier manuals yet...

Four hundres hours later it seems to be working fine...in my engine... /forums/images/graemlins/smile.gif