Hey guys. Not trying to beat a dead horse here and I've searched on the forum but haven't found what I'm looking for. Quick story- bought the truck around 2 weeks ago. 1998 Ram 1500 QC 360, 150,000 miles. Changed oil, trans, diff. A few hundred miles or so after I changed the oil I checked the level and it was down about a quart. I checked it after I changed it and it was right on the money. I had a quick look down the plenum and it's dirty but I didn't see any pooling of oil or anything. No spark knock and doesn't seem to be any loss of power. Truck has very light smoke that usually can't be seen while running. I was driving home the other night and could see a little bit when I took off from a light with someone's headlights. Twice it has had a little visible smoke on start up. I haven't done a compression test yet but I should be able to in a few days. If that's good I'm leaning towards valve seals. The only other thing I can think of is when I changed the oil I put in synthetic. I don't know the history of what oil was used in the truck but could that basically be why it's burning so much? Of course once it started burning that much I added conventional oil. I can't afford a quart of synthetic every few hundred miles lol. I also replaced the PCV with a mopar pcv and that seems to have helped also. It has definately slowed it down some. Also I removed cat when I ran true duals. Any thoughts/comments appreciated. I'm sure I'll know more after the compression test.

 

First things first, with 150k, you should definitely do you plenum. If that's not the main cause to your problem, then it's one of the main contributers to it.

 

If your compression test comes out ok, yeah, plenum is blown.

 

Ok thanks. I was planning on doing the plenum later than sooner but I guess that'll change . I read through the plenum thread and didn't know if that applied to me since the only symptom I have would be the excessive oil consumption. Honestly I wouldn't know if the truck was down on power though since I just bought it and never really drove another one much. I know they're not rockets though lol.

 

So putting the synthetic oil in it probably wasn't the reason? Could it have contributed to it?

 

Synthetic oil won't hurt anything, but, it WILL find whatever small leaks you have.

 

Synthetic oil does a great job at wicking away engine junk. The only problem with that is that high mileage engine's have lots of junk that help block leaks. That's the simplest way to explain it.

 

Ok did the compression test today. Not exactly the results I was hoping for. Cylinders 1,2,3,4,6 were at 160 psi dry. Cylinder 5 was 170 psi. Cylinder 7 was 145 psi dry and 160 psi wet. Cylinder 8 was 120 psi dry and 140 psi wet. Those were the only 2 I did both wet and dry test. Also spark plugs on cyl 1-7 looked good. Spark plug on cyl 8 had all kinds of crap all over it. I don't even know how to describe it. Looking at the pics in the Haynes manual it looks like ash deposits and oil all over it. It's amazing the truck ran as well as it did. It still runs fine and idles smooth. What would be the best cost effective thing to do?

 

My spark plug for number eight was the same way. Sounds like you need to do your plenum gasket. Check out hughesengines.com. They have a new aluminum plenum pan you need so it never happens again

 

+1. What zje said. Your plenum is blown.