Puzzeled about oil

[Khyron]

Re: Puzzeled about oil

Dictionary.com: Thinner : to reduce viscosity.

As oils get colder they get more and more viscous. As they heat up, they get thinner and thinner (less viscous).

Sort of like cold honey vs hot honey. Or maybe syrop is a better analogy.

The first number is how thick it is at some standard temperature (room temp?) . So for example, the 15/x would be thick, the 5 and the 0 would be quite thin. So as an example, lets say 15 is heinz thick ketchup, and 5 is honey.

The 2nd number is "what the oil acts like at some hot standard temp". I think it's 350 degrees but I dunno (we'll use that).

So an X/30 oil is as thin/thick at 350 degrees as a 30 (very thick) oil would be at the same temp (still, its bloody hot so its still really thin!). So the higher the 2nd number the better it is at hot temps because if an oil becomes too thin it's useless. It needs to coat.

Now the problem is of course, in a perfect world you'd have a super thin oil that does not turn to sludge at -40, but also does not turn completely runny at hot temps. That's the holy grail. However, the closer you get to said grail, the faster the oil breaks down. Which is why 0/x oils are relatively new on the consumer market. But the lower the first number, the thiner it will be (or should I say the less oozy/syropy it will be) at cold (-30 ) temps.

Ps that's just from memory, I can look up some of the articles if needed.

Khyron

[1.8Trip]

Re: Puzzeled about oil

I think the first standard temp is 0C and the second is 100C. I also thought that the main advantage of Synthetics was the ability to maintain optimal viscosity over a larger temp range.

[Tuna]

Re: Puzzeled about oil

Well Hey, I may as well get on here too. Regarding the wall mart coments, I used Mobil 1 5-30 in my Rado, bought it at wall mart, in a Silver jug, don't know about 40 but I still have a litre sittin here and it was def. from walmart, under 7 bucks a litre (cheaper if you buy the 4L).

Oh, and someone mentioned "using synthetic will make your engine leak oil" now on a new engine that is rediculous but there is a belief that running synth will find leaks (usually refering to older cars with several thousand K). Now although I won't completely stand by that claim, when I changed to synthetic, my 'Rado, a short time later started leaking oil. Now, I don't think for a second that it's because I switched to synthetic, but i suppose it's possible that due to the properties of synth it's possible for it to find leaks? But I could have no idea what I'm talking about.

[Flanders]

Re: Puzzeled about oil

Khyron, we're both speaking the same language. I know my oils, and appears you do as well. I have a hard time with some people preaching that an oil is "thin" when it's really just a property of the oil at a certain temperature. I mean, at 0C, a 5w is just as thin as a 0w (I can't remember what temp's the 0w starts getting better than the 5w). I'm not gonna harp on this because it seems like my definitition of "thin oil" doesn't match the dictionary's :P I'm not trying to contradict your post though, because we're both saying the same thing

From the oil analysis results I've seen (and been a part of), the 0w that's been in my car(s) have yet to break down due to being too thin. yay for synthetic oil technology!

[Khyron]

Re: Puzzeled about oil

Yah I figured it was the same - I just like smaller easier words.

I'll find the study that showed 0 weight oil after some stress test and a 5 weight. The 0 breaks down faster - not visibly, I mean the interal chemestry breaks down - I don't remember the science (and didn't care).

The main advantage to synth is it lasts longer than conventional. Ie, before the breakdown process. With synth, you can drive more kms between changes with no adverse effects. So for highway drivers it gets you more between changes. It doesn't really help for aging tho - oil after a year is crap, regardless of whether it's synth or not. So I change mine every 6 months, regardless of whether I have 5K or 12K since last change.

Khyron