What would of caused My oil field cap to blow off
Back pressure. Yet no CEL on?
A clogged PCV system will cause a buildup of pressure. Much worse when the engine is old and worn with lots of blow-by.
The crankcase vent has become a popular topic lately.
Someone neglected to install the oil cap after adding oil and the guilty party is telling you that it must have just blown off.
I’ve seen it happen. I was driving a 4 cylinder Ford Fairmont, a company car, and it broke down and the oil cap blew off.
One would think that the oil dip stick would blow out before the oil cap?
I’ve seen more dipsticks blown out compared to oil caps myself. Most caps these days twist and lock don’t they?
A faulty PCV valve (cheap) or the engine has a lot of blowby due to being worn out. (expensive)
If the oil cap; was tight it should not blow off and in most cases the oil dipstick will get blown out of the tube first.
Yes, that has been my experience for several decades.
However, the OP’s question had to do with an oil field cap, rather than an oil fill cap, so perhaps this issue is best left to the companies that perform oil field exploration.
A gusher no doubt @VDCdriver.