Ive been noticing that when I start my car cold it runs really good, can feel it pull harder. But as it warms up it loses its pull gets kinda sluggish. Of course it needs a rebuild due to it having more then 250xxx miles maybe more. My odometer stopped working around 225xxx and that was 4 years ago. But still runs good no problems.My question is, if I switch to a much heavier oil will my performance not fade away as it warms up? Right now I have 10 30 in it. The way I see it is, when cold start the oil is thick= runs better, when it warms up it gets thinner=runs sluggish. Is this correct? Kinda confused with the 10w 30 number weights Viscosity when cold and warm.

 

Hi, I have been thinking the same thing myself, I've just changed oil to 5/30 and it's noisey up top, noisier than the older 1 year old 3000 mile oil. Can't remember what was in it before though , I'm guessing it must have been thicker . I don't want to waste the oil I may try an additive .

Where is you air filter located ?

 

Heavier oil most likely will help maintain high oil pressure when it warms up, as i have seen this on my old 305 car and my turbo car. But i dont think it will help performance

Only way to do that would be mess with the tune aka air fuel and timing. Theres a good chance when cold it runs abit richer and or in open loop. It may need retuned for optimal performance but hard to say

 

Here's my intake Yeah makes sense for it to be noisier with the lightweight oil.

 

Well higher oil pressure equals more power right? What oil would you recommend for my 3.1. I have never ran heavier oil. Always have ran 5w 30.

 

No pressure does not mean power. It has nothing to do with it. Infact it may lose power with too much pressure since it should be harder to turn the pump

Lower weight oil typicaly makes more power than thicker weight tho. Watery type viscosity stuff is used in some racing to bring out as much power as possible since it reduces drag on parts and easier to pump through motor. But motor has to be designed to run on it

 

So running a heavier oil wont do me engine any good?

 

Hi there,
I would recommend running the same weight oil, but synthetic instead of conventional oil. Forget all the voodoo about oil molecules clinging to metal better, etc. The reason for going synthetic is because it maintains its rated viscosity at lower and higher temperatures. Good enough reason, BTW. I have been running it in my 2.8 for the past 3 years, and it purrs like a happy cat. Still has good oil pressure at 140K miles too.

 

Ive had synthetic 5w 30 before and recently went back to conventional 5w 30 on my last oil change. How about running a heavier synthetic oil? Everybody says you should run a heavier oil when you have a high mileage engine and I wanna try it but don't know which synthetic, 10w 40 maybe?

 

Sounds like your bent on using heavier oil in your car. I have to agree with the advice the other members gave you, stick with the 5w 30 oil viscosity has nothing to do with engine performance. I would recommend a good additive though which I used in the past, it's called engine restore. I've used this stuff in some of my high mileage engines and it really works. It takes about 500 miles to kick in and you have to add it at every oil change. https://www.summitracing.com/parts/r...ese2-_-restore

 

Yeah I was, I was under the impression that as the engine ages, the bearing clearances need the heavier oil to fill the gaps??? But yeah seems like everyone agrees on synthetic 5w 30. So yeah that's what I will be going with. My car smokes a bit at startup, sorta white bluish smoke, someone mentioned that its the valve seals so I was wondering if high mileage syn oil would be better than regular 5w30 syn to help with the leaking valve seals. I lose a bit of oil every now and then also with coolant. Do you guys think its time for intake manifold gaskets? Car has over 250xxx miles. And what do u guys think about cutting the gaskets were it says don't cut?

 

250k is amazing but I wouldn't invest any money into fixing the motor, you would be better off in a total engine rebuild or finding an engine with lower mileage. A little bit of smoke at start up does sound like the valve seals and the only fix is to replace them. I would just keep changing the oil when needed and go for the 300k marker.

 

 

Yeah, when it blows I will be swapping in a 3.4. But so far its not showing any signs of slowing down.