Bottom line on Diesel/mixed fleet oils for gasoline engines?

[Drew99GT]

I've tried searching through here to find it, but have come up with inconclusive results. Some say the increased ZDDP will eventualy kill your cat, others say that the increased calcium will offset that. What gives, especially in an oil burner. I believe it was CHJ, board member, that majorly reduced his consumption with Rotella 5w-40, even compared to HM 10w-40. Will an oil burning engine kill a catalytic converter faster with a HD mixed fleet oil? Also, some gas specific oils have as much, or more ZDDP and even calcium than 5w-40 Rotella. Wouldn't they kill your cat faster as well?

[ January 16, 2004, 06:59 PM: Message edited by: Drew99GT ]

 

[theguru]

I would be more concerned with excess oil going through the Cat than the additives themselves. An oil that reduces consumption can only help.

 

[Doug Hillary]

Hi,
as a user of these oils in various petrol engines for over 40 years with excellent results, the description tells it all - mixed fleet!

A specific "Diesel engines only" oil - and there are a number ( Castrol selling at least three in OZ ) should not be used and for a wide variety of reasons. Some of these are related to engine design factors - some to the oil's chemistry
The reasons are not necessarily mutually exclusive either

As long as the oil's container states "Mixed Fleet" which is backed up by the API "S?" rating in the secondary role. All will be well as long as the S? rating conforms with your engine manufacturers recommendations!

Currently I have a 2.5 Subaru Outback, BMW Z3 2.8 and a Porsche V8 on Delvac 1. And other miscellaneous vehicles and engines too

Regards

 

[theguru]

I would agree Delvac 1 is an excellent oil

 

[Robbie Alexander]

quote:

---

Originally posted by theguru:
I would be more concerned with excess oil going through the Cat than the additives themselves. An oil that reduces consumption can only help.

---

Agreed.
Now, you can reduce it by thicker oil, that's one way, but going too thick is not good either.
What engine, or do you have an engine BURNER and HOW MUCH is it burning, and is ALL of the loss due to burning alone?

 

[TC]

I agree with Doug -- if it's an "S" oil, it's formulated to be compatible with your engine, including anticipated circumstances such as a bit of oil burning. Some comparative numbers of deposit makers to help ya:

ROTELLA
Ash: 1.47%
Zinc: ?
Phosphorus: ?

CHEVRON DELO 400 ("Low Ash")
Ash: 1.34%
Zinc: 0.14%
Phosphorus: 0.126%

CHEVRON SUPREME
Ash: 0.9%
Zinc: 0.103%
Phosphorus: 0.094%

 

[JohnBrowning]

It is not realy the level of additives so much as it is the volitility of the oil. If an oil is burning off at an alarming rate it is going to vaporize more additives and send them into the Cat then an oil that does not burn off so easily. Whith that said it stands to reason that a high amount of additives mixed with a low grade oil that burns off easyily would not be a good idea! This is one of the reason I do not like 5W30 oils especialy if they are conventional!

 

[TC]

Good points, John...this phenomenon would primarily (or at least partially) be reflected in the "Sulfated Ash" spec, correct?http://www.petrotest.com/products/database/product.php3?id=AD0000482M01e

 

[Ken2]

Sulfated ash is a lab test that can give ambiguous results. The sulfated ash level is primarily a result of the metal salts used as detergents, but the choice of magnesium or calcium makes a big difference...Mg results in an ash that is abrasive. Ca leaves a soft, fluffy ash that is oil soluble. Either will show as sulfated ash, but the magnesium ash is more problematical.

The phosphorus that gets to the cat will eventually render it useless. Diesel engine oil has more phosphorus than oil labeled GF-3 for gasoline engines. Yes, volatility is partly responsible, as is oil that gets past rings and into the combustion space.


Ken

 

[Drew99GT]

quote:

---

Originally posted by Robbie Alexander:

quote:

---

Originally posted by theguru:
I would be more concerned with excess oil going through the Cat than the additives themselves. An oil that reduces consumption can only help.

---

Agreed.
Now, you can reduce it by thicker oil, that's one way, but going too thick is not good either.
What engine, or do you have an engine BURNER and HOW MUCH is it burning, and is ALL of the loss due to burning alone?

---

Vehicle in question is a 94 Corolla with 80,000 miles. Burns about 1 quart every 1500-2000 miles depending on driving conditons. It's kinda weird actually; it burns about 1/2 quart fairly quickly then stabalizes to a slower consumption rate. No seal leaks I can see; valve stem seals seem to be ok. Never a puff of blue smoke that I can see. I think it's just sliding past the rings. Burns the same with 5w-30 or 10w-30, so I doubt volitility is the problem. Consumption seems to be slightly less with 5w-30 high mileage. I think I'll just stick with the high mileage oils so I won't risk screwing up an emisions equipment or an 02 sensor possibly. I just put the Rotella 5w-40 I bought into my Mom's car, and it only burns maybe 1/2 quart in 3,000 miles with 95,000 miles on the clock (3.8L Olds 88). Although I doubt 5w-40 is too thick for my Corolla.

 

[Valk1500]

Ok Drew this is scary, the wonders of the internet have us pondering the theories of oil consumption befor we ever leave home? Just kidding, wish I could have had this info back when I was younger, heck I'm only learning about oil and I'm 41. Now that I think of it, would be nice to have that 72' Malibu again so I could mod it and finish the dream.

[ January 17, 2004, 05:14 AM: Message edited by: Valk1500 ]

 

[Robbie Alexander]

quote:

---

Originally posted by Drew99GT:
-*-* I just put the Rotella 5w-40 I bought into my Mom's car, and it only burns maybe 1/2 quart in 3,000 miles with 95,000 miles on the clock (3.8L Olds 88). Although I doubt 5w-40 is too thick for my Corolla.

---

I would try the Delo oils either Delo or Rotella or Delvac or one of the others... Mine I know would help as sure as the sunset, Bob's more than likly could help too... I would give it a whirl...

This is what I'd do with your choices:
A: Put in a 15w-40 delo type oil (mixed fleet)
OR
B: Try a STRAIGHT weight oil (maybe first a 30)
or
C: Mix a couple Straight weights with one or two Milti of the same above.
or
D: Lastly and it is lastly try a VII or other additive type product... but in reality its the worst way to attack it.

Consider at least one OCI with a 15-40 or a straight 30...

 

[widman]

I believe in the extra protection of the mixed oils. I drive hard in bad conditions. With the results I posted the other day on my Toyota with Delo, I don't see any reason to consider changing. In almost 7,000 km the dipstick wasn't down even 3 mm, and with 10 ppm of iron in that distance it will be forever before it burns anything.

 

[Steve S]

If the adds kill the cat ,they are much less cost wise than to replace the engine IMO.