Dips in oil pressure when outside temperature is higher than usual - any ideas?

[dmperfection]

Hey everyone; on my 2002 Tahoe 5.3L; yesterday was abnormally hot (about 95 to 100 degrees, and noticed my oil pressure dropped a little and performance was affected. I was driving in slow, bad traffic, A/C blastin', when I noticed as I accelerated there was a loud wooshing sound coming from the engine, like a heavy amount of air was being blasted through my engine. Anyway, I checked gauges and noticed that my oil pressure gauge wasn't at it's normal reading; not completely way off, just off by about 10 psi(?), and I wasn't really getting full power. At idle when stopped, the oil pressure dropped to about 30psi, and no more than 45psi when I accelerated from a dead stop; however, if I continued to keep RPMs up, it eventually got up to about 50 psi, but it felt like I was really beating her up to get up to that reading. My normal readings are just over 40psi at idle, and when taking off from a dead stop, it's normal for pressure to go up to under 60psi. I don't mess with oil change indicator light, and have religiously done my oil changes at 3k miles using high mileage Mobil 1 since 70k miles; I'm now pushing 170k miles. I'm still running 5/30 weight oil, but adding a little Lucas oil stabilizer to thicken up the oil a bit; I never add more than 1/4 quart of Lucas. I burn about 3/4 quart of oil at about 2k miles after each oil change, but I always make sure I top off ASAP - I believe I've read that this is normal loss for these trucks, even up to a quart about 2k miles is supposed to be normal.

So, back to my question; would it be normal to have a drop in pressure like this? Signs of oil pump starting to wear?

Other info to take into consideration; has never overheated, and pretty much replaced entire cooling system, minus radiator about 15k miles ago; pump, all hoses, temperature sensor - therefore, I'm relying on these fairly new parts to let me know I'm not overheating.

Any feedback would be appreciated.

Thanks everyone.

 

[M3PO]

I was driving in slow, bad traffic, A/C blastin', when I noticed as I accelerated there was a loud wooshing sound coming from the engine, like a heavy amount of air was being blasted through my engine. ....... and I wasn't really getting full power.

That loud noise is the fan clutch engaging the fan, thats good, its doing it job! When the fan is fully engaged, you will notice some power lose, as that fan takes a lot of HP. (this is why so many on here switch to electric fans).
I don't hold a lot of faith in the stock gauges, especially on these particular models, they have all kinds of lighting and stepper motor issues. Your oil will thin with high temps, but if you are worried about a drastic drop, have a tech check it out.
If it were me, I would keep on rolling.
If its any consolation, my Denali voltage shows sometimes over 14 and sometimes closer to 12. I think that part of the gauge is starting to fail. I can turn every option known to man on and its high, I could be cruising highway speeds with nothing on, and its almost down to 12. My friend, a tech, checked it out and said it was fine.

 

[Rivieraracing]

How many miles ago did you last change your oil? Also I assume that you have checked your oil level when it is cold and it's all topped off and full?

 

[A623Z]

Mines been doing that too here in Phoenix, It's been a good consistent 115-118 degrees here so the girl's taking a beating

 

[04SS99Denali]

thats completely normal. as oil gets hotter it gets thinner which will show a loss in pressure. and the big air sound is your clutch fan engaging to help cool down

 

[bottomline2000]

That's why I went to electric fans. Its ez to spend an hour in city traffic and the stock clutch fan sucks since our trucks idle so low. Temperature probably started creeping up and computer started pulling timing too.

 

[Cartwright]

You are fine. It's nothing to worry about Like said above here in PHX we get hot and I mean really hot. We have been 110+ For the last 3 weeks. My 02 does this all the time and its nothing out of the ordinary.

 

[Cartwright]

You are fine. It's nothing to worry about Like said above here in PHX we get hot and I mean really hot. We have been 110+ For the last 3 weeks. My 02 does this all the time and its nothing out of the ordinary.