5w20, My .02

[acdaazn]

Originally Posted by dallas

The car calls for 5w30 whay would you use a 5w20, and shorten the life of your engine.
Using a 10w thinner oil is only worth around a .02 mpg improvement. Car mfg are using a lighter oil to meet CAFE ( corporate average fuel economy ratings). A car manufacturer must get a average fuel milage rating for their entire auto line or they pay millions of dollars in penalties. As the engine gets hotter the oil thins, thinner oil has less internal friction, hence better mileage, but under fast driving and high rpm the thin oil layer can be spun away so you have metal to metal contact. More important than the brand of oil you use is the oils viscosity. If you really want a lighter oil find a 5w30 that is lighter at 100C, or a 5w20 that is heavier than others at 100c All oil spec sheets will show the visc at 40c and 100c compare brands and find the right oil but in my opinion a 0-20 or 5w20 is just too light if you plan on keeping the car beond the warrantee period.

http://www.yarisworld.com/forums/showthread.php?t=5744

If they approve it, and it gives better MPG, why not? They "should" cover the engine with this grade of oil as well.

[dallas]

Originally Posted by acdaazn

http://www.yarisworld.com/forums/showthread.php?t=5744
If they approve it, and it gives better MPG, why not? They "should" cover the engine with this grade of oil as well.

In 2000 Ford speced 5w30 for the focus next year it was 5w20 no change in engine clearances, its strictly for CAFE. having access to tribologists that blend and make motor oils I can tell you if you want less engine wear provable with oil analysis stay with 5w30 or 0w30. If you want to save .02 mpg go with the 5w20. Both oils will make it through the warrantee period.
I have not done oil analysis on this engine but I tride the 5w20 on one of my other cars and my metal content increased in the engine oil, indicating more wear was occuring.

[dallas]

Also someone mentioned it seemed to not perform as well toward the end of the oil change interval, it makes sense as your relying on the additive package for protection and additives depleat, specifically the ones designed to reduce friction to save gas, in cheaper oils the mileage increasing additives depleat after only a few 1000 kms. Yes your fine with 5w20 but if you drive aggressively, or live in a warm climate, and judging your on the forum you must like to mod the yaris, I would suggest you stick with 5w30.

[dallas]

As Toyota sells more Tundra's the new "gas hog" in their product line, they will need even more fuel saving strategies to meet CAFE Reqirements .Toyota is one of the better ones, I think it was Ford or Chev that pays millions every year in penalties because their cars dont get enough mileage. The O.E.M's pressure the oil companies to come up with better energy efficient oils all the time, but there are always trade offs.