Cling and viscosity?
- Thread starter Dr. T
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My Bosch mechanc says so. How strong is a cold 0w or 5w film anyway? I say use the heavier W oil when possible, like 10w. 15w-40 GTX is the only oil used by VW mechanics. Dello 400 15w-40 might offer the best start-up protection and long-lasting engine cleaning.
That's the thing...we worry about "flow" at startup...yet, it still takes some time to get the oil to re-coat the parts...however, think about how well WD-40 coats...(it's like water). ie. you're depending on the boundary layer to work.
How about having the oil coating already there as being more important than "waiting" for one to come...
How about having the oil coating already there as being more important than "waiting" for one to come...
"Do thicker oils "cling" better than thin ones? Is this of any benefit? Would it be safe to say that thicker oils such as a 15-40 would retain more of a film thickness/coating on parts during startup than say a 0-20?"
"How strong is a cold 0w or 5w film anyway? I say use the heavier W oil when possible, like 10w. Delo 400 15w-40 might offer the best start-up protection and long-lasting engine cleaning."
I've noticed that if it is just a few hours, then the my truck with 15w-40 will turn right over, as if the oil "clings", but if it sits overnight, and all the oil runs back down into the sump, then the starting is more difficult...I use Delo right now, but am going to switch to Delvac or Long-Life to see if the molybendum in these two oils makes any difference after the truck has been siting for awhile..
It will be interesting to see what others on here say.
[ October 01, 2003, 01:14 PM: Message edited by: Jelly ]
"How strong is a cold 0w or 5w film anyway? I say use the heavier W oil when possible, like 10w. Delo 400 15w-40 might offer the best start-up protection and long-lasting engine cleaning."
I've noticed that if it is just a few hours, then the my truck with 15w-40 will turn right over, as if the oil "clings", but if it sits overnight, and all the oil runs back down into the sump, then the starting is more difficult...I use Delo right now, but am going to switch to Delvac or Long-Life to see if the molybendum in these two oils makes any difference after the truck has been siting for awhile..
It will be interesting to see what others on here say.
[ October 01, 2003, 01:14 PM: Message edited by: Jelly ]
MolaKule
Staff member
let's say the engine is hot on shutdown. The oil's viscosity will be thin, so if it didn't have any surfactants, it would drip off, no matter what the original viscosity.
Most modern oils, whether dino or synthetic, have a small amount of clinging surfactant to maintain a bulk oil presence after engine shutdown. Now at the thin film or molecular level, an oil with esters will provde more wetting over the surface, since the clinging is done at the molecular level, and not the "bulk" level.
I think one needs to examine the differences between bulk oil (macroscopic view) verses thin films at the molecular level (microscopic view).
Most cars and trucks need FM and AW adds to be deposited in the heads. It is the additives that protect on startup until the oil flow is established.
Most modern oils, whether dino or synthetic, have a small amount of clinging surfactant to maintain a bulk oil presence after engine shutdown. Now at the thin film or molecular level, an oil with esters will provde more wetting over the surface, since the clinging is done at the molecular level, and not the "bulk" level.
I think one needs to examine the differences between bulk oil (macroscopic view) verses thin films at the molecular level (microscopic view).
Most cars and trucks need FM and AW adds to be deposited in the heads. It is the additives that protect on startup until the oil flow is established.
Molakule as you know about these things: how about polarity aspects? Perhaps this is one aspect of the VW 505.01 spec for PD engines that is critical to very high pressure applied to splash lubricated parts....Hence a semi-syn seems to be the blend of choice by e.g. Castrol, Millers and Motul (to name but 3) to meet 505.01.
Jelly - You did not say what truck you have but you might want to consider that the fuel situation is very important in starting. Over a longer period of time the fuel system tends to lose its pressure or bowl go dry if it is a carb. Then it takes a little longer for the engine to get a fireable mixture.
'92 Chevy. 4.3L V-6 with throttle-body fuel injection.
It does take a little longer to start after sitting for awhile, and it's a little more noisy.
Also, I had about two seconds of the tapping/clicking sounds (lifters?) last night...it was about 45 degrees when I fired her up. (Geezz...I just mentioned the tapping/clicking sounds the other day in a post, and now it has happened to me...I'm jinxed!)
I'm either gonna have to give up Delo (oh no!) and go to a lighter grade, or try Delvac or Long-Life with their molybendum and see it that makes a difference...
[ October 01, 2003, 03:39 PM: Message edited by: Jelly ]
I am sure you have picked this up in other discussions here, but the anti drainback valve is a critical part of getting fast pressure up to the top on these engines. Preferably one with a silicone (red colored valve) visible through the holes. Good luck
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