Hello All,
Just purchased my first Duramax, an early 06, dual cab, 4X4 with a six speed auto. The truck has 44,300 miles and has a remaining extended warranty. Going to use it to haul a VW desert racer on a dual axle trailer with a combined weight of about 4700 lbs.

I have changed the oil and filter, fuel and trans filter, but not trans fluid as it looked and smelled fine.

Oil pressure at start up with Castrol syntec 10-40 is about 80 psi. Hot and running over 60 psi, idle or down hill about 35 psi. Is this normal?

Sometimes when starting out there is a hard shift into second gear.

When going down a grade I have a slight vibration (slight hopping feeling)that seems to come from the rear, like the tires are over inflated.

The steering wheel seems to have a slight "bump, bump"to it when going into driveways and turning very sharp at slow speeds.

Other that these items, its getting so much better fuel economy than my 1999 GMC with the six liter gas that I can't beleive it.

I have only driven it a few hundred miles but have fallen in love with it. I would rate it as nice as our Dodge Sprinter motorhome.

Thanks in advance for any suggestions or help that you might have.
Jeff

The oil pressure is normal

Does the shifting get better after it warms up? If so I'd call that normal too

Check the inflation and overall condition of the rear tires if you think there's a vibration

I think there is a recall or a service bulletin on the steering but I'm not sure/

I also had a 6.0L GMC and it is a night and day difference... best of luck with your rig

Oil pressure is normal.

Trans may need shift adapts reset...local dealer or shop can do this at a minimal cost..check fluid level.

Steering "bump" is steering shaft and lower column bearing worn and need replaced

And I would rate the D-Max 1000 times better than any Mopar product...lmao.

Thank you for the speedy replys.

The trans does shift much smoother after being driven a few miles.

The tires were new to the vehicle when I got it. They are not a brand name that I recognized. I assume that the the old lease holder replaced them at turn in with these cheapies. I will get them re-balanced next week.

My GMC had a recall for a steering shaft, am I correct in thinking that this is the same issue as the earlier GMC?

I also agree that the steering bump you are experiencing is from a worn ISS(Intermediate Steering Shaft) and lower column bearing. It is not a recall, however, because it is such a common issue many dealers are replacing them after the 3/36 warranty. If for some reason they don't replace it the parts are about $100 on Gmdirect.com and they are very easy to replace. There is a do it yourself article on this site, just do a search to find it. There is also a clamp fix many people do for this as well. It is so easy to replace that I just replaced my own...just make sure to replace both...if you just replace one the clunk will come back.