5/10w-XX

[Alcibiades]

Is there any situation where a car spec'd for 10W-30 should NOT use 5w30 or 0W-30instead? It has been suggested here that 10W-30 is essentially obsolete, but I am unfamiliar with the details of the arguments.

Given what is known about wear at startup, this seems like an obvious question, to which the answer is perhaps just as obvious. But maybe not....

Thanks.

 

[ewetho]

If you get to at least Group II stuff I;d agree it is obsolete. If you are still using Group I oil then 10W-30 would be less likely to sheer. If using synthetic same still applies but at a much lesser extent.

 

[Alcibiades]

I've been running Redline, and probably will continue with that or with Amsoil. I'll have run out of the 10W-30 after my next OC, and thought I might get 0/5w30 instead. From what I've read, Redline seems particularly shear resistant, so it seems like a reasonable move to make.

 

[TallPaul]

Redline 10w30 will easily cold start up here in Michigan, so I don't see any benefit to 0w or 5w where you are.

 

[Alcibiades]

I don't have problems cold starting, per se, but just figured that if the 5W- moves X amount faster when cold, then that is Y amount better for the motor, even in the warmer months. Not so?

The manual states that 5w30 is recommended for the coldest of climates, but the 10W- is prefered. I am just trying to understand why.

 

[Gary Allan]

quote:

---

Originally posted by Alcibiades:
Is there any situation where a car spec'd for 10W-30 should NOT use 5w30 or 0W-30instead? It has been suggested here that 10W-30 is essentially obsolete, but I am unfamiliar with the details of the arguments.

---

In terms of domestic engines there is no synth spec for most of them. In older jeep engines the spec reads "(Preferred)" after 10w-30 with 5w30 also being spec'd. I suspect that these engines aren't suitable for oils that shear to below a 30 weight. That would be my first reaction to an insistance on 10w-30. It may be less of an issue now then it once was.

 

[Alcibiades]

This is a '93 Toyota 7AFE. The car isn't worth much, so I experiment, within reason. I can't afford to hurt it TOO much.

Basically, I'm looking for even the slightest chance at increased efficiency, especially in the winter. She's currently getting better mpg than the EPA estimate for the current model Corolla and Civic, and I want to see how far I can push it.

 

[Compman1988]

Besides, doesn't M1 5w30 actually come out to be thicker at operating temp. than 10w-30?

 

[ARB1977]

quote:

---

Originally posted by Alcibiades:
This is a '93 Toyota 7AFE. The car isn't worth much, so I experiment, within reason. I can't afford to hurt it TOO much.

Basically, I'm looking for even the slightest chance at increased efficiency, especially in the winter. She's currently getting better mpg than the EPA estimate for the current model Corolla and Civic, and I want to see how far I can push it.

---

How long have you had this car? If you had it for a long period of time why change what you've been doing. I see people with cars that are 10 years old with over 200K or more then they ask whats the best for my ride. Unless it was bought used then thats a different story.

 

[Alcibiades]

I've only had it for 55k of its 155k life.

The previous owner was not too smart about maintenance. (After test driving it once before buying, I checked and found the oil to be 2 qts. low.) So I've put some money into it (timing belt being the biggest ticket item so far), babied it, and experimented moderately with it, and now given its present efficiency I think it's healthy. Now, I just want to see how efficient I can make it. At this point I'm definitely inclined to switch to RL 5w30, unless I see a convincing reason not to do so.

 

[427Z06]

There use to be a greater difference between 5w30 and 10w30 in the inexpensive dinos as opposed to quality synthetics, especially for RedLine. However, things have changed the last few years for dinos. A 5w30 that meets GF-4 SM/CF and Ford's WSS-M2C929-A is pretty rugged. I wouldn't hesitate to try it, especially during the winter months. Given the specs for RedLine's 5w20, I'd even give that a shot if you decided to stick with RedLine.