EZ2, bored? feeling a little left out? LOL

 

Viscosity better after a 1000 miles ?
How do you know this ?

 

Actually oils with a lot of friction modifiers in them will get thicker as the FM's shear and become sludge like. Mineral based oil molecules are not uniform and will begin to actually stick to each other creating a thicker oil which now contains burned out sheared sludge like molecules. If you oil is getting thicker and exhibiting higher oil pressure with age then you are probably wearing out the additive package early and a used oil analysis would be a good idea.

 

UOA would be the only way to tell !
Not seat of the pants oil pressure gauge.

 

Viscosity is, in simple terms, resistance of a liquid to flow. That is why I'm using my oil pressure as a rule of thumb on this. In other words, thicker oil has a higher viscocity index than thinner oil. If your oil pressure drops a bit (normal with dino oil) over the first 500-1000 miles, that is because the oil has "broken in", but if the pressure continues to drop over the span of time between oil changes then the additives in the oil have been used up or were not adequate and the oil is not working as well as it should. If the oil is too thin it could and probably will lead to mechanical failures. At the same time, I'd hate to see what would happen if you were to run 20W50 in a car engine designed for 0W20.
This subject is really a lot deeper than I am able to get into because I'm just a regular working guy. I have limited education in physics or chemistry. Any info I post on here I believe to be true, but I surely reccommend that everyone do their own bit of research and make your own decisions. I probably didn't have to say that...I'm pretty sure you guys would make your own desisions without me suggesting it.

http://en.wikipedia.org/wiki/Viscosity

P.S. Valvoline's site explains it pretty good. KB, Valvolines site says just the opposite (in regard to the FM's breaking down and getting thicker)
http://www.valvoline.com/carcare/art...=ccr20040601ov

 

True. But the OPG will give you an initial indication that your oil is thickening. UOA will confirm.

 

Yes, but if the oil was getting thicker the pressure would be higher, not lower.

 

Exactly, you change your oil and notice 1-2000 miles later your oil pressure is 10-15% higher? Time to look into why. A UOA is only $22 at Blackstone Labs and will tell you if your oil is oxidizing before you do any real serious damage to your engine. If you are using generics I would definitely do a UOA at 2500 miles to know how they were performing.

P.S. Valvoline's site explains it pretty good. KB, Valvolines site says just the opposite (in regard to the FM's breaking down and getting thicker

Most oils will get thinner and lose viscosity when they shear but some will actually get thicker after they shear and the sheared molecules oxidize. Once the sheared molecules overheat and start sticking to each other then the thickening starts. Most people change their oil before this happens. That is why synthetics are better. The molecules in synthetic oil are all similar in size/shape and have less of a tendency to stick to each other. Plus syn oils usually contain less viscosity index improvers (VII's) that oxidize in the first place.

 

I never said my pressure went up, it didn't. The pressure dropped indicating that the viscocity was lower than it was when the oil was new.
The pressure went back up when I added the oil treatment. It raised the viscocity of the oil.

 

Oh, I misunderstood. Most of those oil tretments are simply heavier viscosity oils with plasticizers in them and not much anti-wear additives. Some people on Bitog have done virgin oil analysis of lucas & stp and the add packs were not too robust and all they were doing was diluting the additives in oil in the engine they were mixed with. They do abate noise well as they are thicker. If you are using the ST HDEO 15w40 then you will get lower oil pressure than with a 20w50. I don't like to go below a 20w50.

I have heard they sell the Brad Penn in W. NY state for under $3/qt if you buy case lots. If this is true I will probably go that route (I have family there) since that oil while a dino has a ton of zddp which is ideal for a Harley engine. But you never know...I may find another redline closeout before I run out.