I use Mobil-1 in an one of my vans with high unknown mileage. I think that
it is best to flush the engine with a couple of oil changes over 500 miles
before swapping out to 15/50 Mobil 1. All multi grade oils have detergents
and is far cheaper than flushing with the top of the line lube. I also add
MM ( Marvel Mystery oil ) one or two heat cycles before the oil changes.
This brakes down and suspends the crud just in time to drop the oil I like
the minty fresh smell too
As good as Mobil 1 is I still change it 3 times a years regardless of the
mileage due to the byproducts of combustion that build up in the crankcase

Bob Donalds
Boston Engine

----- Original Message -----
From: "Allan Streib" <streib@CS.INDIANA.EDU>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, April 05, 2008 3:25 PM
Subject: Re: Why are the lifters so hard?

> Mobil-1, if you don't choke on the cost, does a good job at cleaning
> sludge and varnish out of the engine over the course of a few changes.
>
> Allan
> --
> 1991 Vanagon GL
>
> Mike <mbucchino@CHARTER.NET> writes:
>
>>  They should be hard during/ after running; they will leak down over
>> time just sitting. The adjusters must have been improperly set, if
>> the lifters pumped up to the point where the valves were unable to
>> fully seat.  Now that they're fully 'pumped-up', you should be able
>> to set them a little looser, which you seem to have already
>> done. The lifters have a non-return check ball that allows oil
>> pressure in, but won't let it out.  The lifters are basically a
>> small 'piston' inside of a 'cylinder'. The inner 'piston' can get
>> stuck on varnish deposits or dirt particles in the 'cylinder',
>> rendering the adjustment capabilities useless.  Hydraulic lifter
>> engines need to have the oil/ filter changes done religiously due to
>> this fact alone.  Dirty oil will force you to overhaul these
>> delicate mechanisms before the normal timeframes.  Some people pour
>> in oil additives to 'clean' their lifters.  Maybe this is good
>> remedy for your engine?
>>
>