Dear friends:

Do you believe using diesel oils (with its extra additives) to replace the regular engine oils (SH, SL ...) in gasoline cars may adversely affect catalytic converters and potentially cause emission control failure? Is there any confirmed evidence of this relationship? Thanks.

Eric

There is belief in some quarters, based on some evidence, that certain oil additive combustion byproducts may degrade catalysts. For this reason, the level of some additives, including zinc-based antiwear additives have been reduced over the years in oils designed for spark ignition engines.

I use HD diesel engine oil (API service category CI-4) in my precatalyst cars, however I continue to use SL (in process or being "upgraded" to SM) oils in my catalyst cars.

If you have a catalyst car that has very low oil use - say less than a quart in 4000 miles, I don't think a CI-4 oil will cause more rapid degradation of the catalyst, but that's just my personal opinion based on various arguments I have read about catalyst degradation issues.

The argument is somewhat slippery - something akin to blaming global warming solely on CO2 production from fossil fuels, when science does not fully understand the complete mechanism of global climate change. We know it has happened in the past, and it may well be happening now, but the bottom line is NOBODY understands why.

Duke

i have 3 benzs... and one is a diesel and i put what i have on hand in when i am changing oil...

diesel oil has more detergent and it has the ablity to suspend ash... that is its main function.... is ash suspension.... ash acts like sand inside a diesel engine....


i have a saab convertible and i changed the oil last week.... i saw a 5 qt jug of castrol 5w30 diesel oil and i thought i would use it.... what the heck...

well the turbo went out in about 100 miles..... they say the turbos have a lot of coke around them and this oil probably loosened up the coke....


so you might want to be careful...

that it was about to go out anyway. sorry about that.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Oh no! I've been using Chevron Delo 400 in my gas engines for about 18 years. Does this mean they are all ruined? Oh no, my 300E only has 280,000 miles of running this stuff so now it's going to an early grave? Oh no!

Seriously. The universal grade oils that you speak about are some of the best dino oil that can be poured into any engine, diesel or gas. I have never replaced a catalytic converter and have gotten excellent engine life from:

'88 Corvette 125k miles
'88 300E 282k miles
'98 4 Runner 185k miles
'94 Windstar 105k miles
'92 Cub Cadet 200 or so hours

This is a partial list of only the gas vehicles that I have run it in with absolutely no ill effects. As I said I have NEVER had to replace a catalytic converter on anything.

Now, none of thes vehicles used oil. If you have an engine with blowby, that is the only way that oil can enter the combustion process anyway. Use good oil and change it often and your engine should never experience blowby, thus no cat problems.

Have a great day,

it could be related to a worn engine and using oil that is too thin. in a worn engine i always use the heaviest oil that the mfgr recommends for my driving conditions. your 5w30 might be too thin. in that engine i would think that i would be using 20w50. i think that is what i used back in my saab 99 days, and neither of mine had more than 120,000 miles.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The original poster never said anything about this being a worn engine.

Have a great day,

The best HD oils (Delo, Rotella, Delvac) are all-fleet oils which means they are suitable for gas or diesel, just use the proper viscosity. Any oil will foul the catalyst in a smokin' crop-duster engine. I'd hope that none of us would let our cars degrade to that condition.

230/8

A good friend of mine works for Chevron back in Texas. He's one of the engineers who works with the "additives" in their different quantities to formulate oils for different applications- in short a sort of oil chef. I picked his brain about oils on a road trip- and it bored my wife to sleep (literally).

Here's what he said, (if my memory serves me correctly)- and please don't flame me on this, I'm just passing on HIS opinion and our conversation as I remember it (and I'm thinking the opinion of an engineer who works in lubrication for industrial apps is usually worth more than...well... the guy in the auto dept at Walmart, but then I could be wrong).

1. ANY oil changed at regular intervals will provide better "lubricity" (whatever that is) than an oil left-in too long.

2. Synthetics are great, but expensive. Old formulations used to cause problems with some gaskets and rubber, and distorted their shape- causing leaks and oil burning in older engines. Newer synthetics do not cause this as much anymore- they've corrected for it.

3. Synthetic blends? Were partially formulated because of #2 above, and no longer provide much benefit over regular dino oil, just cost more.

4. Diesel oil is formulated to reduce "soot" in the oil of a diesel motor- and can be formulated to run for long periods at high temps (like in industrial apps). Because it retains the flow characteristics of regular oil, yet reduces "soot" it helps keep passageways clean. SO- many oil engineers run diesel oil in their gasoline motors. (He obviously is a proponent of Delo 400).

5. Keeping a synthetic oil in a motor for longer periods and changing it less frequently is generally a bad idea, especially if the driving is usually in heavy traffic at high temps. The synthetic "base" (?) and some additives of many synthetics cannot hold up to that sort of use. SO- the longer you leave it in, the less protection you have.

6. Oil works best (whatever type it is), and the additives hold up longer if it flows at higher oil pressure, and is cooled by a car moving/circulating/cooling it's oil at say, highway speeds than moving slowly at low pressure in a hot motor at idle for long periods. So- a driver that is able to run only at highways speeds MAY be able to stretch the oil changes a little bit. The guy in the car that is in stop and go traffic for long periods everyday, with the ac running, and the window down- with his bad (insert repulsive style of choice) music blaring as he screams "Hey Dog!" into his cell phone between drags off his cigarette- which he blows into the open windows of the cars around him, and punctuates by intermittently spitting out the window.... (You know this guy?) Well, his oil SHOULD be changed MORE frequently (regardless of what he's using).... but instead he goes to quickie mart and dumps another 99 cent quart of 30wt in his "ride"- which will steadily increase it's spew of blue smoke as time goes on.

7. Diesel cars should NEVER run on regular dino oil for long. In a pinch- it's better than dirty old diesel oil, but the motor creates "soot" that the reg oil can't handle- which degrades it much more quickly, and can cause increased wear internally, in addition to "deposits."

So- I'm running Delo 400 now in the 190d. He runs it in his Acura. I still use the synth in the wife's Nissan, but I pay much closer attention to the oil change schedule on both cars than I used to. If I could keep the 190 out of the shop- it would be getting close to oil change time too.... -J

Satyr,

Great post.

I started using Delo 400 about 17 or 18 years ago. Not too long after that I answered an ad about something and it turned out the guy was an oil additive formulation expert and the owner of an additive company.

He asked what oil I use and I told him Delo 400 and his response was a surprised "Really?" I thought he was about to tell me how bad it was, but he started telling me the opposite. He said that it tested as one of the best oils money could buy. I asked him about gas engines as well and his response was a very affirmative "for ANY engine."

I have stuck with it for most everything, but have moved toward synthetic for a few new cars in the family that call for a lighter weight oil.

If anyone were to see the insides of my engines whenever they come apart and examine the wear surfaces, I think they would be sold on the stuff pretty quick.

Have a great day,

Larry, is Delo 400 available in other weights? I mean 15w40 is probably a good choice for midwest summer climates (50 - 100F) but not really for winter (-10 - 50F) where 5w30 or 10w30 is probably a better bet.

Thanks!

To my knowledge Delo 400 is only available in 30W and 15W40, but in other climates it might be available in other weights.

I am under the impression, however, that the truckers use it in 15W40 year round in all climates.

Have a great day,

where do you get delo400?


my saab has a great engine... but i used gunk engine cleaner then put in a diesel castrol oil in it... so i think that i loosened the coke that would be in the oil lines going to the turbo.... i just bought the car and the engine was
in very good shape with 140 k miles and it looked like it had not been to neglected.... but i know that engine oil flows to the turbo and i think that by cleaning the inside of the engine and then using a high detergent oil i probably loosened some turbo sludge and ruined it....


about 15 years ago i ruined a buick by using resoline so when you do the inside engine clean thing you have to be careful.... i recently did it on the m103 right before i changed the head gasket and the inside of the engine was beauitful.

Most NAPA stores carry Delo. If you can't find it, they carry Mobil Delvac at Wal Mart which is about the same thing.

Good luck,

well if we are talking about the best oil
it looks like airplane oil would be best..

i use to fly and i know that they use good oil..


AEROSHELL OIL W100