motor oil and oil pressure

[Keywest18]

well i just changed th oil in my blazer for the first time since ive had it about 2 months.and i noticed before my oil pressure fluctuated a lil bit never really paid attention to it to much.well ive been readin and for high mileage vehicles people were running synthetic(ive always used conventional 10w40) well i went to walmart and got some synthetic 10w30 Q state.well now at idle my psi is at 20psi but driving and over 1000rpm its at 40.my oil light doesnt come on and i dont think its that big of a deal but i just want some reassurance as i know oil and oil pressure is very important.also what oil do you guys use and why?

[backlash]

That gauge will drive u crazy. It varies so widely because of ambient temps, load and othe factors. About the only time it's consistent is when you get to cruising speed and stay there, it should be fairly predictable. Just make sure u check the dipstick regularly. It's more reliable. I use rotella for my diesel.

[Keywest18]

yea driving its consistent at 40psi and ive been checking the dipstick regularely even tried thickening it up with some 20w50 lol

[bay_slayer]

once you go to synthetic, you cant go back to regular oil. and dont mix conventional and synthetic.

[Keywest18]

why cant u go back? why not mix the two? isnt that the same as a synthetic blend?

[Montauk17]

Originally Posted by bay_slayer

once you go to synthetic, you cant go back to regular oil. and dont mix conventional and synthetic.

I have to disagree...I ran pure synthetic in my truck for one oil change and didnt like it for my own reasons. As long as you don't run it for several oil changes,mainly in a motor with some miles on it your ok. The problem is synthetic has alot of detergents in it that will break down oil and carbon deposits. If you don't like it switch back to regular or a synthetic blend on your next oil change. I do agree not to mix the two though.

[Montauk17]

Originally Posted by thegr8cody

yea driving its consistent at 40psi and ive been checking the dipstick regularely even tried thickening it up with some 20w50 lol

That is big time overkill. I assume you have the 4.3 v6? That motor does not need anything more than 10-30,factory calls for 5-30.

[Keywest18]

i kno the factory calls for 5-30 but most vehicles do.but my dad runs 10-40 in everything over 100k miles.i havent noticed an increase in valvetrain noise but im not a fan of the fluctuating oil guage.soon as some oil goes on sale im changing it again.

[melanconga]

The different viscosities. Want mix and the squash factor is different for each weight of oil.they go by bearing clearance. For your oil weight. Blends have chem.added to make them mix. I run q state 10/30 in winter and 10/40 in summer in a f350 with 460. Have 300000 miles on it

[scott craft]

It used to be bad to switch between conventional and synthetic because they had different swell characteristics for the seals but from what I understand they both affect the seals the same now.

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