I would also like to know if there is an easy way to tell what group an oil actually is. I also use a "full synthetic" Petro Canada oil in my truck. Would like to know if it actually is...

 

I used Amsoil in my '01 for 535,000kms with no issues and great service.
Put it in my '07.5 at 25,000kms, a dealer switched the oil ( whatever they might carry) when the truck was towed in ( sat for 3 weeks waiting for parts) for a plugged DPF.
Shortly after the oil change, it began to leak oil around the CCV cover on the top of the motor, and is running down the back of the motor and dripping on the road.
I'm not certain that the leak is related to the oil change, but the timing is funny.

 

Isn't Royal Purple a Group V oil? Extremely good lubricating properties, but shorter life? (closer to conventional?)

 

IIRC Schaeffer uses about 25% Group IV or V synthetic base stock and for Royal Purple I don't recall what they use. Mobile One has several different synthetic oils out now so its hard to know for sure what they are selling you. Castrol, Q State, Penzsoil and Rotella are 100% Group III Dino oil unless they have made changes that have not been reported. The only oils that I know who make 100% synthetic oils are Redline and Amsoil. I will say that Amsoil does make some oils that are not 100% synthetic oil like there XL line for cars and a synthetic blend 15w40 diesel oil.

 

why are synthetic oils not recommended until 20K. the diesel mechanic i go to said the engine doesn't break in properly, is that correct? if the lubricating properties are greater in synthetics, does that hamper the breaking in of the engine. Amsoil is plugged a lot on the forums, but haven't seen engine breakin addressed

 

Id go about 1 more oil interval on petrolium before I switch over. But thats just me.

I dont trust those oil change sensors at all. Amsoils 5W-40 is CJ-4 rated for the 6.7. My dad runs it in his 07 6.7 and with 45K, no problems....except oxygen sensors and PDF problems. ( told him to find a 12V)

The main advantage to synthetics is extended drain intervals and if you wanna get your moneys worth and stretch that oil life instead of chaning it on a schedualed interval list, which sometimes is sooner than expected, get on an oil analysis plan.

 

Thanks for all the replies. Lots in information. I have decided to wait until my next change at 23,000 kms.

 

Not sure what you mean by shorter life...
I think I remember that RP is a Group IV and PAO oil and does have really good Lube properties... What shortens the Syn oils life is the additive package being depleted... By condensation (water) Fuel Dirt Soot etc... The additives trap the contaminates and keep them from causing damage in the motor.
Conventional oils have the same dilemma except they start breaking down at about the temp's that the average engine operates at... Meaning they start breaking down immediately which is why it is recommended that you drain the oil every 3000 miles on the average vehicle with only a gallon of oil in it.. More with those that contain more.