Date: Sun, 7 Aug 2022 08:41:55 -0700
Reply-To: Dan N <dn92610@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dan N <dn92610@GMAIL.COM>
Subject: Re: Engine oil
In-Reply-To: <BL0PR05MB4916888E5958F43248E67C84A0609@BL0PR05MB4916.namprd05.prod.outlook.com>
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thank you Dennis,
I wonder if there's something to do with the oil grade they recommend with
the RPM of the engines... On my ML430 suv it's about 2K rpm at 70mph... On
the vanagon it's 4K at 70mph. At 55mph it's about under 2K rpm for the suv
and about 3K rpm for the vanagon. The suv uses 5W40 synthetic, I use
non-synthetic 20W50 on the vanagon.
On Sun, Aug 7, 2022 at 7:37 AM Dennis Haynes <d23haynes57@hotmail.com>
wrote:
> Recently there was some discussion on engine oil. So I'll add more
> thoughts to the discussion.
> Recently I acquired a 2022 GMC Sierra Crew Cab, Denali. Has the 6.2L and
> 10 speed Allison. Will soon be having its 1st oil change done. Part of GM's
> plan to improve fuel economy is the use of low viscosity lubricants. The
> engine calls for 0w-20, the transmission use special low viscosity ATF, and
> even the axles call for 75w-80. I having a hard time wrapping my head
> around using the 0w-20 oil for an engine of this horsepower. To add to the
> confusion the hopped version of this engine for the Corvette calls for
> different oil.
>
> So doing some research I learned something that I never gave thought to.
> Engine oils contribution to an engine going into pre-ignition. Makes sense
> given some thought. There is always some oil on the cylinder walls and some
> part becomes part of the combustion process. For the Waterboxer this is
> relevant as there is also some oil laying in the bottom of the cylinder.
> For my engine it has active fuel management, (AFM). Glorified cylinder
> deactivation. Under certain load and speed conditions the cylinders get
> deactivated via a dance of turning off the injectors, and de-activating the
> valves. In this state oil that gets past the rings isn't burning off.
>
> GM addresses this as part of their Dexos specifications. The oils
> contribution to detonation is also of concern for engines that are direct
> injected and turbo charged.
> So to add to the confusion there is Dexos 1, generation 1, 2, and now 3,
> and Dexos 2. Now one would think that Dexos 2 would be the later or
> improved spec. It is not. Dexos 2 is for europeant vehicles which addresses
> that many European vehicles are Diesels. The performance for spark ignition
> engines is actually lower. The GM specs also include other ratings that
> also include fuel economy. Oils that carry the Dexos 1, generation 2 or 3
> rating is limited.
>
> How does this apply to us? There are a number of folks that think heavy
> duty Diesel oils are a better choice for the Waterboxer. The pre-ignition,
> detonation control is just another consideration for using oils that are
> designed for gasoline, not diesel engines. Pre-ignition is the cause of
> most melted pistons and a contributor to rod bearing failures. For the
> Vanagon it is of significant concerns as due to all the other noise and
> design of the engine it is not easily heard when it occurs.
>
> Dennis
>
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