same 4.8 Vortec I've posted about before, now at 150k miles on the clock. It now does longer trips daily, 50 miles one way to work and 50 miles home. My friend was inquiring about extending his oci, how does either M1 HM 10W30 or Castrol 0W40 for a 7k oci sound? I'd use either a tough guard or ultra filter. I was also considering QSUD 5W30 or 10W30, I've heard nothing but good about those two oils on here. Any reasons to worry about the 0W40 thinning out too much in 6-7k miles?
10W30 or 0W40
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I've been putting VML 10w30 in my father-in-law's 1500HD (6.0) for 3? years now with him keeping almost no eye on the OCI or oil level, and change it roughly twice a year which works out to 12-15K - the odometer on the truck is broken but last time the dash came to life it was 230-something so it now has right around 300K on it and the engine runs great. So 7K on a synthetic 10w30 sounds like a premium diet for the 4.8.
its a 2011, its the 4.8 with VVT
I would consider 10W-30 PYB for that duty cycle. Stout conventional oil.
Originally Posted By: mobilaltima
its a 2011, its the 4.8 with VVT
5w-30 and 10w-30 will be a whole lot easier to find on sale and just as good.
10w30 Pennzoil GOLD blend for 7,500+ miles
Castrol 0w40 for 10k miles.
OR
Mobil1 0w40 for 10k miles.
OR
Mobil1 0w30 AFE for 10k miles.
OR
Castrol 0w30, if you can find it, for 10k miles.
Those would be my oils of choice if I owned that vehicle and wanted to stretch OCI safely.
That far South of New Orleans it's always warm. A 10wXX oil will do fine year around. With a 100-mile round trip daily, an excellent candidate for an extended run oil. If he wants Mobil, M1 EP is a better option than the Castrol, IMO.
Nick1994
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Originally Posted By: tig1
Try M1 5-30 for 10K OCI if his driving is normal. What year is it?
I would personally choose a 10w30 over a 0w40, I just like oils with a narrower visc spread as they seem to hold up better (not that a good 0w40 can't or anything) but I know a 5w40 or a 10w40 always starts to make my lifters tick a thousand or so KMs before a nice mineral blend 15w40 does!
Being all the way down south I don't think you'd gain too many benefits from using a 0W and you are able to take advantage of a more robust oil with less VIIs 
I like the Mobil 1 10w30 high mileage but if you can’ find M1 or Castrol 0w40 on sale, use that with confidence.
Originally Posted By: mobilaltima
Any reasons to worry about the 0W40 thinning out too much in 6-7k miles?
Originally Posted By: Vladiator
Castrol 0w40 for 10k miles.
OR
Mobil1 0w40 for 10k miles.
OR
Mobil1 0w30 AFE for 10k miles.
OR
Castrol 0w30, if you can find it, for 10k miles.
Those would be my oils of choice if I owned that vehicle and wanted to stretch OCI safely.
Castrol Magnatec 10w30 has about the best NOACK of any 10w30, 6.9.... with a 100c viscosity of 11.6cst. Should be fine for 7.5k miles, up to 10k
The castrol edge 0w40 is about 12.9cst @ 100c, and is BMW LL-01 certified, so it should be generally good up to 15k miles unless the car has excessive blowby and acidifies the oil.
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