Switch to Synthetic Oil - What Mileage?

[WyoDutch]

What's the general consensus as to how many miles a new Duramax engine should have on it before going to a fully synthetic motor oil?
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I always did it at the 6,000 mile mark on Harley V-twins, but I'm thinking I will hit 10,000 on the DMax before I switch.
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Thanks in advance.

[Mark Rinker]

I guess there is no concensus on this one, Dutch. Go with your gut and change at 10K.

[WyoDutch]

I guess there is no concensus on this one, Dutch. Go with your gut and change at 10K.

I was going to go with Red Line 15/40 diesel oil (which I've used for years in my 6.2)... but after doing some more research.. I'm opting for Rotella T-6... primarily bacause of the low ash additives.

Figure the T-6 with an Amsoil 25K filter should cut my oil changes to a semi-annual ritual.

[topfueler1]

Run Amsoil 15-40 Diesel 100 percent Synthetic the best. Become a preferred customer like I did. You get it for wholesale sent to your door in two days. I also run the Amsoil EaO synthetic oil filter. Amsoil is the best you get the best protection and mileage!

[More Power]

What's the general consensus as to how many miles a new Duramax engine should have on it before going to a fully synthetic motor oil?
.
I always did it at the 6,000 mile mark on Harley V-twins, but I'm thinking I will hit 10,000 on the DMax before I switch.
.
Thanks in advance.

There was a discussion a few years ago at GM concerning whether to pre-fill all of the Duramax 6600 engines with Mobil Delvac 1 5W-40 synthetic from the factory. They do this with the Corvette engines.

There are lubrication engineers and others I trust who say you can pour in synthetic from the very beginning, and that no break-in time is needed. Personally, I'd not do it for a while cuz I like to change the oil within 1000 miles of new to remove any manufacturing particles and assembly lube. From that point on, use whatever meets the powertrain warranty. ;)

Jim

[rustyk]

Synthetic oil has no effect on breakin. Piston aircraft engines do need a breakin period, exprcially if a cylinder has been replaced, or if it has chromed cylinders.