.....So 0w will flow better then 5w at super cold cold temperatures
However for this example lets use we are comparing a full synthetic 0w vs a full synthetic 5w
At a temperature of 50-60F, would they both flow the same? Or is 0w still better?
In general, if you take a bunch of oils that are otherwise meeting the same other specifications, a 0W20 and 5W20 viscosity curve will be slightly different on average throughout the temperature range. I don't know why there are some members here who like to try to pretend like this isn't case. Yes there are also examples of 0W oils that are thicker along much of the curve than some 5W oils..... especially say, a 0W30 A3/B4 type oil that has a high HTHS target for a 30 weight, vs say, a 5W oil formulated for a fuel economy HTHS target, but that's a different sort of comparison. Assuming all other things are equal, it is reasonable to assume that on average, a 0W20's viscosity curve will be thinner overall than a 5W20 except where they basically line up near operating temp. As long as you don't say it out loud, or draw any conclusions from this reality, then you'll be fine... Woops...
would it also be said that a 5w oil would 'stick' to surfaces more then a 0w? albeit a very tiny bit but still some?
When you turn off the vehicle after running it long enough to be up to normal operating temps, both a 0W20 and 5W20 are going to be about the same viscosity and both are going to leave behind about the same amount of oil on surfaces as most of the oil drains down to the sump. By the time they cool off enough for any viscosity differences to show up, it no longer matters, because the parts in the engine already "dripped/drained" down while the oil was hot and thin.
im afraid to say but since i am trying to learn i wont be shy
so my toyota has the 2.5l engine with vvti, and basically everyone in the world seems to have the rattle on startup for 1-2 seconds since oil pressure is low at startup. the noise dissapears within 2 seconds when oil pressure was restored. since most of these vehicles are running 0w20 i was thinking if maybe 5w30 would have a higher film strength which would lower the rattle compared to the water thin 0w20?
Some cars do not have an anti-drain-back system in place to keep oil in the passages leading to the various oiled components in the head, or the design of a specific component causes the oil to drain out of it normally. This is pretty common. The "solution" to the problem you're describing would come from placing an anti-drain-back valve in the path of the oil between the pump and the head or offending component within the head so that the moment the engine is cranking, the oil is already there and the pressure comes up instantly.
With that said, I question whether it's actually a problem that needs to be solved, and I can pretty much guarantee that any change to your oil selection that can
meaningfully resolve this startup noise is going to be an oil that is not suitable for the rest of the engine. The solution isn't going to come from a grade change or a Euro oil or anything. You'd need some truly snot/honey levels of sticky up there in the noisy part of the head to make it "stick" and quiet things down, but the rest of the engine can't run on that.
thanks!! since it ran 0w20 its whole life im leaning to 0w30 or 5w30 since i don't wanna jump up in viscosity all of a sudden. i really wanna try a euro 5w30/w30 with high hths which is basically a thin w40 but am hesitant since havent read much others doing that in this engine. seems like im the only scapegoat. even tho i doubt it will make a diff just too shy to jump that high so i finally convinced myself to start with a thin ish 5w30 or 0w30
As previously mentioned in the thread, at your ambient temps, an oil pump is going to move about the same amount of oil per revolution of the engine whether the oil is 0W20 or or 15W50, and so, will take the same amount of time to reach the noisy mechanism that needs oil pressure to work right.
ahahah its so hard for me to just pull the trigger but ill do w30 now and then maybe by next oil change ill be ready to jump to 40
If anything oil related stands a chance of quieting down that engine on startup, it's probably going to be an "old" formulation... something with less "dry" base stocks, and more lower group level oils and older "snotty" add packs that seem to carry a bit more of that surface tension tackiness. If you want to go down the mostly pointless rabbit hole of trying to fix a hard part problem with liquids, Try a 10W30 conventional or synthetic blend, optionally a "HM" formulation. Castrol GTX or Havoline... Havoline can be ordered through walmart in 6qt garage boxes for about the price of other 5qt jugs from walmart. Good value there. In my experience fancy 0W synthetics don't make for quieter engines. I can't stress this enough, none of these oils are going to solve that problem, but might make it slightly quieter...