i have just changed my oil in my 94 4.3L s10 blazer for the first time since i bought it. it was realy black and was glad to change. but lately it's running just below the 40 line on my gage and at higher speeds it's been dropping. is this just from the tranny shifting? or is there something wrong. it also looks to me that the oil is in the operating range when i checked.

 

Well that seems a little odd generally pressure should increase as you step on it. Mines like 60 when cold and once engine is hot its 40 at idle and goes to like 55 when I step on it. I run full synthetic 5W30 through it so might change it some. When you said that it looks like its in operating range I take it you mean the hash marks on the dip stick. I would check itafter itssat around some these dipsticks seem like they aren't in a great place they seem to get splashed.

 

So long as you don't drop below 8-10psi at idle and are over 20psi past 2000RPM, you shouldn't have any problems with lubrication. Does the oil pressure fluctuate when you are at a constant RPM or are you just watching it as you go up through the gears?

 

i am watching it at kinda both. i understand it fluctuating shifting gears but is also does this inbetween gears

 

The real question is what did it do BEFORE you changed the oil and did you also change the filter?
If it was more normal before you changed it, say 35-40 at idle and 55 at 1000+ rpm, thenI would change the filter right away, you will lose less than a quart and if you pre-fill it your lose is essentially nothing.
The factory recommendation for my 95 is 5w30.
An oil filter should bypass if it is getting plugged up.

I send a sample an oil sample to these guys from most of my engines, not every oil change except on the wif's Corvette.
http://www.blackstone-labs.com/

David
95 2WD Blazer
147K

 

like swartikk said as long you dont drop below 8-10psi your good. now if your driving it and the oil pressure remains on 0 psi and you hear clanking noise thats when you worry but try to check for leaks if you feel like your losing oil. but i went threw something similar what i did was an engine flush change all my gaskets ( oil pan,valve gaskets ) and did an oil change an add lucas oil to my 10-30 and havn,t had any problems but good luck to solving your problem