Valvetrain clatter

[Z Ya Later]

Ugh, it just never ends. So, I've noticed since it has gotten colder here that the valvetrain is talking back a little bit. Its esp. noticeable when I start her up for the first time in the morning...really loud, then goes away after a few seconds. This tells me that oil may not be getting up into the top of the heads on first startup. This doesn't happen after she has been run during the day, just after sitting overnight. I'm running Royal Purple 10w30 right now. Should I switch to 5w30, at least for the cold season? Or, am I looking at a more serious problem? Could this be connected to my leak and missing 1/2 quart of oil? Thanks guys.

[Trash man]

change ur oil. colder it is, dirty it is, oil is thicker

[Joe 1320]

I'm running Royal Purple 10w30 right now. Should I switch to 5w30, at least for the cold season? .

Ummm..... you shouldn't be running 10-30 at all. 5-30 is the recommended viscosity..... especially in the cold weather you want something that flows quickly at lower temps.

[fastTa]

During cooler air temps, the polymers that are added to the base oil are coiled up and allow the oil to flow as their low viscosity numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would under the same circumstances. So at 200 degrees F, the oil has thinned only as much as the higher viscosity number indicates. So think of a 20w-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

So the cooler air temps means the oil will be slightly less viscous and not more viscous like most think. But this is only true with multi-viscosity oils and NOT regular oils. This means it takes just a little longer for the less viscous oil to retain enough pressure on the inside of the OEM lifter and pump it up. Thus, the valvetrain noise. As long as it goes away quickly, there should be no problem.

It is unlikely that misssing just a 1/2 quart will affect your oil pressure, but it wouldn't hurt to keep it full. So I would not worry about going to 5w-30.

[Z Ya Later]

Thanks guys. I ran 5w30 when I first got the car and noticed it was kinda noisy. Once I put 10w30 in, it ran quieter, thus I figured it best to leave the 10w30. Any idea what might cause this? Or have I really lost it this time? lol

[fastTa]

Thanks guys. I ran 5w30 when I first got the car and noticed it was kinda noisy. Once I put 10w30 in, it ran quieter, thus I figured it best to leave the 10w30. Any idea what might cause this? Or have I really lost it this time? lol

The larger the split in the low and high viscosity, the more polymers they have to add to the base. This subjects the oil to be more prone to shear and thermal break down. You really want to keep as little as split as possible to avoid having too high of a polymer ratio in your oil. The polymers do nothing for protection themselves, they just help control the oil's viscosity at the warmer operating temps.

[Z Ya Later]

The larger the split in the low and high viscosity, the more polymers they have to add to the base. This subjects the oil to be more prone to shear and thermal break down. You really want to keep as little as split as possible to avoid having too high of a polymer ratio in your oil. The polymers do nothing for protection themselves, they just help control the oil's viscosity at the warmer operating temps.

Then I guess 10w30 it is, thanks Kev . Any idea on how to get rid of that clatter on cold start? Could it be a sign of another problem? Maybe running a mix of 5w30 and 10w30 during the winter?

[Trash man]

its typical as motors get older. the jeep I6 are known for that. everything is a bit looser now. i wouldnt wry bout it, just make sure the gauge gets to pressure not too long after

[Joe 1320]

Just to throw a few more drops of oil into the burn..... oil reverts to it's base viscosity in area of high shear. There needs to be a balance between cold and hot performance, this is especially critical during warm up. This is why in ultra cold climates, a 0-30 is recommended to ease pumping in freezing temps until the engine warms, but it is also not recommended for performance applications. Really, much of this does depend on what kind of cold temperatures you are really dealing with. In my area where we might see 1 or 2 days per season where temps are below 32º, it is not a cause for concern.

Still, it might be helpful to track down exactly where the noise is coming from. LT-1s are notorious for cold start piston slap due to cylinder wall to piston clearance.

[Z Ya Later]

Its about the same here, maybe the high 20's if its a reeeeeeeaaaaaaal cold day. Usually the low doesn't get down much past the 30's, and I'm usually not driving during that anyways, let alone starting her up. My guess was that it was the valvetrain (mainly the rockers) since it would go away after a couple seconds of warming up.

So, straight 10w30 should be fine...right? Are we sticking with that? lol

As far as the oil pressure gauge, it never shows 0 pressure during this. It actually show really high pressure, which I always thought was odd. I've asked this before a couple times and never got an answer...is this normal? After the car warms up, the gauge shows more normal readings (20 instead of 60+ for idle), but its still a little jumpy (doesn't increase or decrease smoothly, jumps around more than anything). Could I have another problem?

Thanks guys for the help thus far.

[94 formula]

As far as the oil pressure gauge, it never shows 0 pressure during this. It actually show really high pressure, which I always thought was odd. I've asked this before a couple times and never got an answer...is this normal? After the car warms up, the gauge shows more normal readings (20 instead of 60+ for idle), but its still a little jumpy (doesn't increase or decrease smoothly, jumps around more than anything). Could I have another problem?

Its perfectly normal. If your car ever shows 0 oil pressure shut it off. The reason its reading so high of pressure is because the oil is cold which makes it thicker (thats probably not the technical term). Picture squeezing syrup out of a bottle that has been in the freezer. You have to squeeze really hard to get a little to get out (like putting high PSI on the bottle to get a little out since its cold), now take that bottle of syrup and put it in the microwave for a minute and watch how little pressure it takes to get the same amount of syrup out. That is why you have the high reading.

[fastTa]

10W-30 is the one you want. You can USUALLY eliminate that cold start chatter by putting about a 1/5 - 1/4 more turn on the rocker adjustment nut. Just don't go too far because you don't want to hang your valves open.

[Z Ya Later]

Good deal, thanks guys. I appreciate the help