oil pressure

[hamburger68]

i changed oil yesterday, went from 10w40 to castrol 5w30. now my pressure gauge is reading slightly higher. not a lot, but i was wondering how that comes. any ideas?

[ApexVIII]

the 10w40 is thicker i believe, then the 5w30 is

[hamburger68]

yes it is, but i'm curious as to how it affects the pressure reading. the oil pump rpm are directly connected to the engine rpm. so the amount of oil pumped at a certain rpm should always be the same. therefore a thinner / faster flowing oil should lead to a lower pressure? ... oops, i just confused myself!

[tblu92]

Doesn't make sense--old school says that a thicker oil should give you a bit more pressure--but with these new formulations You really don't know what the viscosity is with multi vis oils ----a 5/30 VS a 10/40-- who knows what it is at certain temps---I do know that many engine builders absolutely do not reccomend 10/40 on any LS Gen 3 motors--

[Smkn_TA]

Maybe your oil was low before you changed it...

[hamburger68]

Doesn't make sense--old school says that a thicker oil should give you a bit more pressure--but with these new formulations You really don't know what the viscosity is with multi vis oils ----a 5/30 VS a 10/40-- who knows what it is at certain temps---I do know that many engine builders absolutely do not reccomend 10/40 on any LS Gen 3 motors--

thicker oil = more pressure, that's what i was thinkin', too. i switched brands, maybe the veedol reacts a little different from the castrol, other additives or so. i went by the manual, they say a 10w40 is o.k. and the car ran fine. but from all i've read by now, a 30 weight oil is the way to go on the ls1.

Maybe your oil was low before you changed it...

nope, level was fine.

[Sarge]

Simple......thinner viscosity oil will flow more freely giving you better (higher) oil pressure versus thicker.

[hamburger68]

allright, then it wasn't just me. Thanks!

[Sarge]

Many confuse flow with pressure when speaking to viscosity choices and their oil pressure guage.