Diesel oils (CH4, CI4 ...)in gasoline cars and emission issues

[ericnguyen]

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

[Duke2.6]

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

[blueranger]

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...

[t walgamuth]

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

tom w

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,

[t walgamuth]

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