Originally Posted By: Tony10s
Originally Posted By: Trav
Originally Posted By: 19jacobob93
Moral of the story is thicker oil won't always help a rattly engine!
Quite true, I have a little rule of thumb (its not always true either but mostly). If the noise is from the block end below the cylinder head(s) then thicker oils tend to help more than thin.
From the top end thinner usually does better at keeping things quiet. Things like camshaft pitting, worn rocker fulcrums or rockers, galled balls and seats, etc tend to throw a fly in the ointment though.
Noise from the timing chain area can go either way depending on if its chain or tensioner, barring any mechanical damage needing replacement thicker will help slightly with chain noise and thinner the tensioners hydraulic system.
Nice you took a trial and error approach, going up didn't yield the result so you went down and it did.
I also used to think that my Elantra engine ran more smoothly and quietly on 5W-30 oil than it did on 5W-20 oil (I know there's not much difference between the two, but I have also seen other posts and heard others say the same thing about their engines being smooth and quiet on 5W-30 versus 5W-20). The first 5W-20 oil I used in the car was Mobil 1. After using QSUD 5W-20 and NAPA Synthetic 5W-20 and noticing that it ran just as quietly/smoothly on these oils as it did using 5W-30, I no longer have the same opinion. I also believe it can possibly depend on the brand of oil being used. Certain brands may run more smoothly/quietly in certain applications. I have both 5W-20 and 5W-30 in stash ... I won't be buying any more 5W-30 in the future. I am going to run what 5W-30 I do have in the spring and summer ... when it has all been used up, I will use only 5W-20 from then on. Anyway, my car manual says that 5W-20 is the preferred oil for the car (5W-20 is also on the oil cap) ... it says that 5W-20, 5W-30, and 10W-30 (for climates with temperatures 0 degrees F or greater) can all be used, but 5W-20 is preferred.
I think there's a law of diminishing returns on both sides. Or law of diminishing destruction? haha
5w-20 is going to flow a bit better on a cold morning than 10w-30. And if it's cold enough, you can probably get by withotu doing any damage to an engien designed for 5w/10w-30! 0w-16 will flow better yet ... but may damage an engine designed for 10w-30.
5w-30 may make the engine spec'd for 5w-20 run a bit quieter and smoother. No difference in wear numbers, likely. However, if you run up to 40w-70 (literally thicker than gear oil ...) you may start hurting fuel economy and not lubing things like lifters properly.
