questions on 8.1 motor in 2004 Chevy truck

[Alan Roehrich]

I have a 2003, I love it dearly. Wouldn't trade my 8.1 for any diesel of any type or brand.

Some of them have slight piston slap when cold. Don't rev it up cold. It won't hurt a thing.

Some of them use a little oil, maybe 1 quart in 3000-3500 miles. The vast majority of them are actually sucking some oil from the lifter valley under the intake manifold due to the design of the PCV system. It is not getting oil past the rings, or past the valve guides and seals. It's simply picking oil up through the PCV system built into the intake that has the pick up in the wrong location, and a serious lack of baffling.

The PCV system design will cause deposits to build up on the plugs, usually at 25-30K miles they'll look a little rough. Change them, the deposits can cause enough resistance to create a misfire, and could cause enough load to kill a plug wire or coil pack.

I use 20W-50 Royal Purple in mine, and because it is a 2 wheel drive, I use an AC PF 932 two quart filter. My truck will be down maybe 1/2 quart or a little more between oil changes.

At 96K miles I replaced my plug wires with Taylor wires to resolve a slight misfire under acceleration. And I went back to the GM AC Delco double platinum plugs.

It's a tough big block that makes really good torque, with proper maintenance it should go 200K+, and possible 300K+ before needing anything serious.

If you live in an area where they don't require emissions testing, or at least don't look at the exhaust, at least get rid of the catalytic converters, better still, put a nice exhaust system on it, and get the ECM tuned. Power will increase considerably, but so will fuel economy. You can also put a GM 180 degree thermostat in it, big blocks don't like to run hot.