I'm new to diesel's and the mechanics of the 300d but learning quick. Drained the oil a few days ago. Contaminated with charcoal lighter fluid. (That's a whole new story). Took oil filter out today. Noticed there was no oil in the oil canister and hardly any oil in the cooler. Is that the norm when the oil is drained? Also because when I fire up cold start the oil pressure is at 45 lbs but after it runs a while the pressure drops to 15 lbs. Someone suggested the spring in the oil filter canister may be bad causing the oil pressure to drop. I don't even see a spring in there. Removed the canister and no spring in there, nor in the innards of the section that bolts to the block. I took the oil pressure line off and there wasn't any spring there either. No help nor phots in Haynes. Anyone know where abouts that spring should be?

Any help would be appriciated, Jim