The discussion about oil is a bit off in here me thinks...

5W-40 at 100*C is NOT thinner than 15-40 at 100*C they are the same.

A winter rating simply means you get the best of both worlds. The W rating only comes into play when your engine is cold. That rating is given at freezing temp. The issue with oil by nature is that it gets thick when it's cold, in a perfect world, magic oil would exist that has the same viscosity at all temps. Sadly instead oil is thick when cold and as a result, it get's too thick to do the job, it acts closer to sludge or tar inside your engine, unable to get in the small cracks it needs to between the cylinder and rings, unable to get through the pump and up through the tiny oil orifices in the cams that hot oil would easily flow through to protect your engine. This is why thicker is NOT better when it comes to protecting your engine. The same way too thin is an issue too, if it's too thin it'll not handle the load bearing forces needed to keep the metal from touching and your engine components will suffer damage. So what we need, is magic oil that holds its viscosity across a range of temps.

GOOD NEWS!!!! The magic oil is here! W rated oil exists and we all commonly use it! 15W-40 oil means that at freezing the oil will act like 15W oil, which is great because at freezing temp 15W oil is quite reasonable, it acts like say "50 weight" or so. 0W is even better, acting like 0W or so when it's at freezing which equates closer to a 30-40 weight when hot. This means it actually stays very consistent across a huge range of temps due to modifiers that they add to it that were developed in a lab.

The second number is what matters at operating temp, don't think that 40 is better than 30, the engineers know best what you should use. There are some situations like very worn engines where we might benefit from a thicker oil as components wear past their limits and thicker oil fills the gaps so to speak.

BE AWARE..... modifiers fail, a 15w-40 oil will fail sooner than a standard 40 weight oil and when it fails, it'l go to the thinner side not the thicker!!!!! It also will go thinner when it is overheated. For my S2000 Turbo, this is a serious issue as it runs hot and the oil is destroyed quickly putting it at risk given it's high demand hp/liter build. In that case, I have two options, run a 15w-40 oil and change it often as it begins to go thin or run a standard 40 weight oil and don't drive the thing in the cold, or get a block heater etc. so it never runs cold if possible. In the summer, I run a standard 40 weight, in winter, it gets 15W-40 Group V synthetic (real synthetic not the off the shelf "full synthetic" which is NOT a true synthetic) and I drive it only 1000 miles or so in the winter so the issue never arises of it needing new oil.

Sorry that was long-winded but the world has the XW-XX rating all wrong in general.

-Greg

 

This is true however it’s not really much of a shelf and can be damaged so that the sleeve can drop but not all the way down. See my thread on 03 engine failure for pictures.

 

@05TurboS2K Nice write up, it does tend to get lost in all the stuff around oils. Sheer , temp breakdown,etc are actually more important but try and get that info in one handy place

 

It does appear that liner is lower than block deck, but it is not the best picture. What does the headgasket material look like on that cylinder, any visible damage...like seeing imprint of movement from liner?

Normally, a lifter will be at a different rate of cadence than a slipped liner, quicker and lighter, and a slipped liner will be a bit "heavier" sounding and slower cadence. And increase as engine reaches normal operating temps. Normally, a exhaust leak will be opposite...noisier when cold and diminish as it gets warmer...to the point it may even go away. Plus, a liner or lifter will usually have a definite "metalic" element to the noise...whereas...an exhaust leak is usually a little more of a "chirping" sound.

 

I know what the science says about oil viscosity which is why I prefaced my remarks... However I also know how many times on this forum people with a "lifter or sleeve noise" switched from a lighter oil to Rotella 15w40 and had their noise disappear.

It is a cheap fix in many cases.

 

Sure, there's a little lie in the modifiers, they don't work precisely but they're close in most cases, you might net some small gains enough to assist the issue. A better bet would be lucas oil additive if you really want to improve it using this method, it makes a substantial difference. I've used it to shut up a TCT on various cars that have hydraulic driven tensioners and it worked so well it made me nervous to think how much it thickened oil up though they claim it to still be able to spray the same through oil skirt coolers under pistons etc.

Hmm, on that note, it's probably worth adding a bunch to the oil and seeing if the noise is suddenly gone. If it is, you know the problem isn't a sleeve, case closed. Then one could fix the issue as they see fit.

Anyone tried seafoam in the oil for a few min to clean up noisy lifters? I've had mixed results there personally.

 

@05TurboS2K Never tried seafoam, but I have a light tick at about 197 deg you could only hear standing at the front of the disco at idle, vanishes as soon as the RPM hits about 800. It was there with 10/30 and still there with the 10/40. I have considered trying an additive but my oil pressure is solid with the 10/40 and that tick could be so many things. I may try some additive if I have to top up, but now that I found most of loose pan bolts that could be a while.

 

Richard, best thing for you is a 180 degree thermostat if it starts at 197, but I seem to remember you already have one?

 

@Extinct Yup I am running the Black right now, I rarely hit 197 and itne Inline mod is just waiting for me to have time. It does not bother much, I suspect the PO neglected a lot of things and these old pushrod engines can tick, I figure if an additive quiets it down, I will try the cheap filter followed by flush next oil change.

 

I could be wrong but in BC I bet you would never see 190 with the inline. My disco holds a 100 degree temperature difference from ambient without issue.