1988 Chevy S-10 Oil Runs Up The Dipstick

when driving 55mph or higher my oil pressure goes to 60-80
when i get home oil has ran all the way up my dipstick. I have checked for water in it possibly and havent noticed it milky looking or anything. I also replaced pcv valve. What else could be checked or needs to be done to find out why my oil keeps going up my dipstick? I read something in a haynes manual for this, and it says something about a charcoal canister needing to be cleaned. would that cause my oil to come out of the dipstick?

Response:
It could be, the canister is located on the radiator core support, has 3 vaccuum lines on the top, and a fibre filter on the bottem which is open, and approximately 6 inch diameter. Note 1 of the vaccuum lines goes to the PCV valve and follow your emmission diagram on the core support. But, depending on the mileage and driving habits, I suspect piston blow by. Run a compression check both wet and dry. Check the color of the spark plug electrode. And finally, do a vaccuum check. Have you ever noticed or wondered why Preformance vechicles have taller or multi vented valve covers? It's so the crankcase can breathe at higher RPM's. They also have a larger oil pan that holds as much as twice as normal.If the crankcase can't breathe then it fills with gases and builds pressue. That pressure goes the path of the least resistance. In some cases the dip stick tube, others, seals and gaskets.