k, so i just did an oil change in my van 20ish miles ago. ive been using mobil1 synthetic for the past 20,000 miles. last oil change was at 99K this one at 104, and i weht to auto zone for my oil/filter and they had a special for oil changes... a 5L jug of oil and a boch oil filter for $16.99. i took that in a heartbeat seeing as though my van is a tank and the filter alone is like $7 and synthetic oil is unholy around here. the oil was castrol high mileage 10w-30. since that change my oil pressure has been screwy. before (i.e. the past 20K) my pressure did this. my 2nd gear starts at 22mph, so at 21 mph i let off the gas, wait a second, the car shifts to 2nd and i get back on the gas. during that happening at 21 mph, before i let off the gas my oil pressure is at 40. i let off the gas and it stays at 40 til it shifts itself, after the shift it would drop down to the mid twenties and steadily rise back to 40 til about halfway through the gear then stay at 40 til third. same thing applies to third fourth fifth etc... since the switch to high mileage 10w-30 that same shift to second goes like this. pressure is at 45 til 21mph, i let off the gas, car shifts to second, during the shift it drops to around 35, after the shift it goes back up to 40 and the second i get on the gas it will go back up to 45. ive never seen this before and im not sure if this is how its supposed to behave. anyone have any idea on any of the following things, my vans busted/ about to be busted, im not supposed to use synthetic, im not supposed to use this high mileage ****, im insane and this is normal for such a switch, i should switch back to synthetic, i can stop being **** and stay with the stuff i have now. any hepl appreciated, especially if you own/owned a conversion van.

btw its a 99 chevy express high top galidaitor conversion with the 5.7L v8.

 

So basically what you are saying is now that you are running the 10w30 hi mi your oil pressure stays higher between shifts?

 

If this is the case its probably due to the fact that you are running a thicker oil(assuming you were running 5w30 full synthetic). GM recommends that you use 5w30 for emissions purposes. By going to a thicker 10w30 you will run I higher oil pressure. A small block Chevy can safely run 10psi of oil pressure for every 1000 rpm’s, however it always makes me nervous with oil pressure that low.

 

KX, this is a normal occurance that happens when you go from synthetic to dinosaur oil. Synthetic oil flows much quicker than dino oil, and typically runs at a slightly lower pressure as a result. So you could say that even though the synthetic is 5W30, since it is much more flowable, you lose a little oil pressure. But it has a much higher lubricity level and minimizes engine wear. Where synthetic really helps is at startup. Synthetic flows much quicker through your engine especially at cold startup, and that is where 60% of engine werar occurs. It also does not produce sludge like the dino oil, and you can go longer between changes as long as you dont drive on dirt roads all the time.
So, the pressure increase is typical, I know this because one time I thought I was saving money, and used dino oil in one of my trucks, and the oil pressure went up some. If I were you, I would stay with synthetic in the future. It will not hurt you van to put a couple of thousand miles on the new oil change if you dont have the money for synthetic right now!

 

baller. im not strapped for cash at all, i just didnt see any harm in saving $30 on essentially the same product. ill prob switch back to full synthetic sunday and keep the gallon and a quarter of "dinosaur oil" for my toys. thanks for the advice