There are technical differences, but for most purposes they mean the same thing. Take a very, very close look at your spark plug tips the next time you pull them out. Do you see tiny, tiny little dots of metal on them?

When I pulled my plugs last year that had a lot of ash and carbon deposits on them. I will pull them again this weekend to see if anything has changed.

The plugs on my F-150 look like a fudgesicle

Another question, the D-150 will burn oil somedays and then it will go for a month without burning a drop. Have any idea what is causing this.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Tough to diagnose without more info, but spark knock and oil consumption go hand in hand -- in BOTH directions.