10-30 motor Oil

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I keep running into posts one here where someone mentions they are using 10-30 oil in their engines.
What are the reasons for dropping to 10-30 instead of 15-40 as the owners manual calls for. In my owners manual it says 10-30 may be used if ambient temperatures are 30 degrees or below. Are you your own warranty station by using 10-30 year round. Need some pros and cons.

Jerry


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1999, 2500 QC 4X4, Driftwood,Auto, Stock, Cab High Shell, Tow Package, Camper Package.

 

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15-40 is the standard above freezing oil for every diesel engine I've encountered-CAT,DD,Perkins,John Deere&Cummins. I personally wouldn't use anything else.

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95' 25004X4,AT,Driftwood,Banks,Warn fender flairs and running boards(Play truck)95 3500,5 speed,driftwood,Banks&phscotty,30,000 GVW apple and tractor hauler(work truck)

 

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Gohon,

One reason for the 10-30 may be because some of the owner's manuals had it that way. My '95 had that error and I asked the folks at my dealer about it. Print mistake, just use 15-40 was their answer.


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Joe George
Eureka, CA

'95 2500 CC auto 4X4,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

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If we are supposed to run 15W-40, why is the regular Amsoil diesel oil 5W-30. The 15W-40 is the marine diesel oil. I am confused now.

 

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The oil experts can speak more directly to the "whys" and the diesel applications, but I'll just throw in this based on personal experience: I was using 5W-30 synthetic (M1) at least 10 years before the owners manuals started calling for it in cars. That 1980 Honda never missed a lick, never used oil, and is still running today without ever being rebuilt - currently about 350,000 miles. If using conventional oil, I would use the weight recommended by the owners manual. With synthetics, I think you can use Amsoil, Delvac 1, and possibly others that have lighter-than-recommended weights and there is no need to be concerned because you'll still have phenomenal engine protection. Plus you may see a slight mileage improvement...

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2001 ETH, QC, LWB, 4WD, 3. 54, SPA Pyro & Boost, Leer Cab-high shell, Rear ARB locker, Psychotty Air

 

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Gohon: If it were warm enough all year I'd keep the Amsoil 15w40, but my truck has to crank when its -20 or colder. I run Shell Rotella 10w30 from late November to spring, then install the Amsoil again.