Why can't "diesel" oils be certified for SL gas engine use?

[ToyotaNSaturn]

After reviewing several UOAs here at BITOG from Chevron & Mobil in the 15w-40 DELO flavor and comparing them to other 5w and 10w oils from Chevron, Mobil and Pennzoil, it seems that the only common links I can find are:

1--Phosphorus is much higher in all cases with DELO's

2--Viscosity is thicker (duh!)

3--Calcium is generally somewhat higher.

Obviously, 15w-40's won't achieve the GF/3 fuel-efficient rating, but, is that it? Are there base-oil properties that go unmentioned?

So many things look similar between "diesel" and "car/truck" oils that it just doesn't make sense NOT to use DELO's to some degree, unless, of course you don't like the thicker oils.

Outside of the marketing arms of oil companies, are these the only reasons "diesel" oils aren't "good" for gas engines?

 

[Jelly]

"Why can't "diesel" oils be certified for SL gas engine use?"

They are...all the big-name HDEO's (Delo, Delvac, Rotella, Long-Life) are API CI-4/SL certified.

I'm a fan and user of HDEO's, and I know of two reasons some people don't use them:

Higher Phosphorus Content - Catalyst poisioning in shorter period of time than "conventional" oils.
Higher Sulfated Ash - Higher level of deposits left behind.

IN MY OPINION, both are over-blown issues that in reality give no real reason not to run an HDEO. As long as the viscosity of the HDEO is proper for your engine, I see no reason not to run them. Simply put, great oils for a low cost!

 

[Robbie Alexander]

quote:

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Originally posted by Jelly:
-*-*-*Higher Phosphorus Content - Catalyst poisioning in shorter period of time than "conventional" oils.
Higher Sulfated Ash - Higher level of deposits left behind.

IN MY OPINION, both are over-blown issues that in reality give no real reason not to run an HDEO. As long as the viscosity of the HDEO is proper for your engine, I see no reason not to run them. Simply put, great oils for a low cost!

---

There is NO engine oil on the planet, that will harm the CAT as long as youre not pouring it in there... normal oil consumption and ANY oil on this planet will not harm the CAT.
As far as the deposits, it can, but a properly formulated oil even with higher Ash will keep it as clean or cleaner than SYNthetic.

I'm in agreement with the rest of what you said, and this point is the kicker::::

Simply put, great oils for a low cost!

[ December 06, 2003, 07:45 PM: Message edited by: Robbie Alexander ]

 

[Ken2]

HDMOs are not listed as ILSAC GF-3 oils because of the phosphorus content and haven't been tested for fuel savings (and probably wouldn't pass that test).


Ken

 

[MNgopher]

As others have pointed out, all the big name Diesel oils (like Rotella, Delvac, and Delo) already carry the SL rating.

One reason folks don't use them is the viscosity - often there is no need for the thicker oil.

These oils do NOT have to meet the phosphorous restriction imposed on most PCMO, as that only applies to oils that are 20 and 30 weights, I believe, as of now.

The higher P content will eventually clog a cat IF oil is being consumed. This is an issue for car manufacturers, as they are required to warranty emissions components for longer and longer periods of time. Back when an emissions warranty only lasted 50,000 miles, a cat designed to last 60,000 miles was OK at the going rates of oil consumption. Now that they have to warranty them out even longer, they will do EVERYTHING they can to prevent emissions failures.

In general, the detergent package is more robust to deal with the additional soot loading developed during diesel combustion.