diesel motor oil in a gas engine

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What are the pros and cons of using a motor oil advertised as "for diesels" in a gas engine? Let's assume it's SL/SM rated, and the viscosity is appropriate for the engine & climate
 
I'm currently using Pennzoil Long Life Gold 15W-40 in my Montero. Biggest advantage so far has been reduced oil consumption and a much quieter engine.
 
I have been using it in my chevys for a while and notice a quieter engine, slightly reduced gas mileage. I track my mileage every time i get gas so over years you can get a pretty good avg. Overall i like it but it dont get all that cold here in nc. in the winter, i prefer something a little thinner just because the HDEO is a pretty thick. The new CJ oils are great for gassers becuase the zddp levels dropped to about 1200. I think alot of it depends on the way the vehicle is used. if it is cold and you jump in and tear off then i would definateally use the thinner oils. I am always cautious and driver very easy for the first 15 mins when it is cold out. You are probably going to get alot of opinions about this. The facts are this, many people have had good use of HDEO in gas vehicles for a long time (300k miles or more). Which is better, who knows. I believe this depends on how the vehicle is used and under what conditions. I know a few people in PA and NJ that use HDEO 15w40 all the time and dont seem to have issues. Personally i believe in cold temps under say 30F i believe the benefits of thinner oil will trump the advantages of HDEO. Especially in newer engines and OHC engines. Just my thoughts.
 
Originally Posted By: bepperb
More zddp causing possible o2/cat poisoning but perhaps better protection for non-roller valvetrains?


I was thinking about this too, but if it had unsafe levels of additives, how could it meet the SL/SM spec for street use?
 
If it is a diesel rated oil first, SM says they can have up to 1200 ppm ZDDP. PCMO is speced at 800ppm.
 
I am and have been using diesel/gasoline oil, specifically Rotella 5w-40 in my gas engines for quite some time; have not noticed any harmful effects. Gas mileage in both trucks have stayed the same, no change.

An Isuzu engine specialist highly recommends the diesel rated oils even in Isuzu gas engines; says the Rotella is the best oil available for the gas Isuzu engines as well as the diesels.

Spoken to several ole time engine rebuilders here in Colorado that also swear by diesel rated oils in gas engines, as long as it's not a new ford, dodge, etc that specifically call for the water-thin type oils.
 
I have a 99 Isuzu trooper I typically use a Diesel or heavyweight auto oil in. It reduces oil consumption at least until the viscosity thins at about 3000 miles.
 
Originally Posted By: tonycarguy
What are the pros and cons of using a motor oil advertised as "for diesels" in a gas engine? Let's assume it's SL/SM rated, and the viscosity is appropriate for the engine & climate.


I have also been trying to get a definitive answer on this. For example, Mobil 1 Turbo Diesel Truck 5W-40's product page reads:

Originally Posted By: "Mobil 1 Turbo Diesel Truck 5W-40"

Applications

Mobil 1 Turbo Diesel Truck 5W-40 is recommended for use in all super high performance diesel applications, including modern low emission engine designs with Exhaust Gas Recirculation (EGR). These applications include the following:


  • On-highway engines operating in both high speed/high load and stop-and-go conditions
  • Off-highway engines operating in severe low speed/heavy load conditions
  • Virtually all diesel powered equipment from American, European, and Japanese equipment builders
  • High performance gasoline engines and mixed fleets
  • Refrigeration units

Specifications and Approvals
API CJ-4, CI-4 PLUS/CI-4/CH-4/CG-4/ SM/SL/SJ


Besides a pair of Saturn SL2s (1998 & 2001), I also have a 2002 Camaro SS (5.7L), a 2002 Toyota Sienna (3.0L), a 2003 Impala LS (3.8L), and a 1965 Barracuda (225). All of the newer cars require 5W-30 oils. Toyota specifies SL/SJ while GM only specifies Starburst. I would like to use a 0W-30 CJ-4/SM/SL/SJ synthetic oil ( Esso XD-3 Extra) in all of them but my concern is with cat/02 poisoining. Since the Starburst seems to have more to do with fuel economy that engine protection, I think I can probably live without API Starburst oils in these engines.

Can anyone tell me if CJ-4/SM synthetic HDEOs will cause cat/O2 failure quicker than the SL/SJ PCMOs specified for these engines.
 
search for delvac-1 and rotella synthetic UOAs and you'll quickly see why its a great choice for my track car.
 
Originally Posted By: fraso
Does your track car have a catalytic converter and does it need to pass any e-tests?


Doesn't matter if it doesn't burn oil.

I run TDT in all my vehicles.
 
Modern Diesels have cats. My '06 (pre DPF) Diesel Ram has a catalytic converter (though I think it's for unburned HC and CO emissions only, not NOx). Is it the NOx part of the catalyst that people are worried about? If not, pour in, drive on, be happy.

Dave
 
My concern is with passing Ontario's Drive Clean e-test. I do not believe diesel e-tests are as strict (smoke test only?) as gasoline engine e-tests.

I was hoping that a synthetic HDEO's higher detergency would help to keep the rings rings clean (especially in the SL2s) and the anti-wear additives would keep the rings from wearing so that oil consumption remains minimal for as long as possible.

I just want to know if a CJ-4/SM HDEO will likely poison a catalytic converter or O2 sensor any worse than a SL/SJ PCMO.

If it does, then I suppose the trade-off is the long-term cost of repairing an engine & cat on a SM PCMO vs the cost of more frequent cat/O2 replacements on CJ-4/SM HDEO.
 
Originally Posted By: fraso
My concern is with passing Ontario's Drive Clean e-test. I do not believe diesel e-tests are as strict (smoke test only?) as gasoline engine e-tests.

I was hoping that a synthetic HDEO's higher detergency would help to keep the rings rings clean (especially in the SL2s) and the anti-wear additives would keep the rings from wearing so that oil consumption remains minimal for as long as possible.

I just want to know if a CJ-4/SM HDEO will likely poison a catalytic converter or O2 sensor any worse than a SL/SJ PCMO.

If it does, then I suppose the trade-off is the long-term cost of repairing an engine & cat on a SM PCMO vs the cost of more frequent cat/O2 replacements on CJ-4/SM HDEO.


Look at my location.

Now look at the mileage on my vehicles.

HDEO's in all of them.

Not a problem with Drive Clean.
 
Thanks. I must have missed the part about running TDT in all your vehicles and thought you were using M1 PCMO from your sig. I'm still getting used to all the oil acronyms
smirk2.gif
. My reply was obviously more directed to n8wvi and his 5.9L '06 Diesel Ram 2500.
 
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