My new theory on engine tolerance design and oil specs

[ZiTS]

The problem I have with the 5w-20 debate is this: Who cares how great the UOA's for this grade are? If it doesn't protect the engine as well as a thicker oil, why use it? Heck, a straight 5 weight would have excellent shear stability, I'm sure, but who would run that in their car? Maybe 5w-20 is more shear stable than 5w30, and maybe I could get 1 or 2 more miles out of a tank of gas. But I'm interested in my engine holding up more than I am the oil. After all, isn't it alot easier to change motor oil than it is to change the motor itself?

I just refuse to believe that the engine in my car, which now calls for 5w-20, can be protected as well as basically the same engine three years ago when it called for 5w30. Not to mention the fact that every other Ford engine requires the same viscosity oil.

Perhaps the 5w-20 is a more "advanced" oil, but the fact Ford made the one-size-fits-all switch in 2001 to 5w-20 has convinced me it was for fuel economy first & foremost, with engine protection ranking somewhere on down the line.

Unfortunately, I guess we won't know for some time how good (or bad) this thinner oil is for engine protection. At least not until someone has a car with well over 100K+ miles on it that's had a steady diet of nothing but 5w-20.

JMO

 

[ZiTS]

BTW, I would like to clarify I'm not trying to imply UOA's aren't important and don't give credible, useful information - so please, no attacks on that front. I simply meant I would like to see some long term, tangible evidence of how 5w-20 protects before conclusions are drawn about its' benefits.

 

[cwilli01SS]

Patman-
You just said a few posts before you'd run redline 5w20 in your Firebird? Did I read that wrong?

 

[Patman]

quote:

---

Originally posted by cwilli01SS:
Patman-
You just said a few posts before you'd run redline 5w20 in your Firebird? Did I read that wrong?

---

That was my opinion a long time ago (you'll notice how long ago it was when I posted that) but after seeing how much my engine likes an oil that is a thick 30wt much better than the thin 30wts, I can't possibly see how my wear numbers would be any good with 5w20. I didn't have as much UOA data on my engine back then as I do now.

 

[Kompressor]

quote:

---

Originally posted by MikeL:
For a resonse to what someone said about thinner oils putting less stress on oil pumps freeing up more power. A few racers i knew used to do that, they claimed that running 0w30 in there cars as opposed to 15-50 would yeild a gain of about 2-4% of power. Although i should also mention that they rebuilt the bottom end of there motors every other season.

---

Thats an excellent point, I also know a couple drag racers that use light synthetic oils, another trick is leaving out several qts of oil for less crank windage (such as 7 qts in a 10qt sump). In regard to the 5-20, I would agree that the manufacturers are after fuel economy more so than long term engine life, after all its only their concern for the waranty period.

 

[MikeL]

For a resonse to what someone said about thinner oils putting less stress on oil pumps freeing up more power. A few racers i knew used to do that, they claimed that running 0w30 in there cars as opposed to 15-50 would yeild a gain of about 2-4% of power. Although i should also mention that they rebuilt the bottom end of there motors every other season.

 

[TallPaul]

Good points JohnBrowning, especially #5. To go with a 5w20 because the 5w30 is going to sheer back to a 20 anyway is to give in--to admit defeat! I bet 10w30 is just about as sheer stable as 5w20 and surely it has a much better high stress sheer number.

[ December 02, 2003, 12:51 AM: Message edited by: TallPaul ]