gm 8.1 engine

I have 80,000 on my 8.1 and it uses 1/2 quart every 1500 since it was born. That is normal usage.

My guess is an over filled engine. The OP says he has to add oil every 900 miles but does not say how much. If it is between the marks it does not need oil!
Randy

martin w wrote:
I have 2006 fleetwood flair with 6000 mi need to add oil about every 900mi . I see no leak on the ground or gray or black smoke.

Wayne

My 8.1 did about the same, but my last oil change I used Mobil 5-30 full synthetic and my oil consumption was cut in half, now only a half a court about every 1000 miles.

I have a 8.1 in a 2004 PU that used a quart in about 1,000 miles sinse new, now AT 34,000 miles. Changed to Mobile 1 10w-30 synthetic this spring. Took a 3500 mile trip to Arizona and back towing a small TT and it didn't burn a drop! Still on the full mark when I got back! What the heck happened?
Was it the synthetic oil or did it just finally get broken in or what?
Still wondering but happy anyhow. 38,000 miles on the clock now.

harold1946 wrote:
1 quart used every 1000 miles is not unusual for thr 8.1 and not an indication of anything wrong.
The 8.1 does not have a PCV valve.
If you have the Workhorse chassis manual it will tell you 1 quart every 1000 mi. is normal.

I burn one quart about every 5-6000 miles with my 8.1L engine. Of course at 70,000+ miles it is well broken in. This is at highway speeds, pulling a toad, and in the Western mountains.

With only 6000 miles, How often has the oil been changed?

Should be changed every 12 months regardless of miles.
With your usage rate at 900 miles it would be due for an oil change not just adding a quart.

Engine is probably not even broke in yet. Needs to be driven.

harold1946 wrote:
1 quart used every 1000 miles is not unusual for thr 8.1 and not an indication of anything wrong.
The 8.1 does not have a PCV valve.
If you have the Workhorse chassis manual it will tell you 1 quart every 1000 mi. is normal.

X-2, my 8.1 preforms the same as Harold's!

1 quart used every 1000 miles is not unusual for thr 8.1 and not an indication of anything wrong.
The 8.1 does not have a PCV valve.
If you have the Workhorse chassis manual it will tell you 1 quart every 1000 mi. is normal.

How much oil do you need to add at the 900 mile intervals? You may find that after you get 10,000 miles or more on the engine, oil consumption may lessen.

I wouldn't get overly concerned unless the oil consumption becomes excessive.

With 80,000 miles on our v10 engine, occasionally I have to add 1/4qt oil or so.

Best of luck and safe travels...

Have you pulled and examined ALL eight spark plugs? This will tell you if it is being burned or not. If it is being burned, the next test is a compression test to determine where the problem is.
If the spark plugs turn up clean, then you can start looking for leaks, which will always happen in places that are next to impossible to see, like a rear manifold or valve cover gasket.
Also, you need to make absolutely positive that you are putting in the correct amount of oil, per the owner's manual, NOT the dipstick. Some dip sticks are wrong and if you put in too much oil, it may quickly be forced out of the crankcase.