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Kent

Les, or anyone -- ?? regarding motor oil

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Kent
I saw this posted on another site, and wondered if it was accurate enough or valuable enough to add as a link in the Resource section. Anyone have any opinions? http://www.vtr.org/maintain/oil-overview.html The foot-draggin' Clubhouse Custodian...

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UCD
Kent It is basicaly every thing that I have been tougt about oil 10w-40 never was considered a good weight oil to run. 10w-30 will stand up to heat better than 10w-40 Anything free is worth what you pay for it This & $1.00 might get you a small Coffee Maynard aka/UCD

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Les
Multi vis oils are made by taking a 10 weight base oil and adding a viscosity modifier, which is a polymer with a very high molecular weight which expands with temperature. As the temperature increases the polymer expands and thickens the oil. I spent 3 years in the oil blending business in the early 1980's. The proper way to make a 10w30 is to start with a base 10 oil and add the proper molecular weight polymer that can only go to 30w with temperature change. Some companies used to use a blend of base oils to achieve the same thing, I certainly hope that no one is doing that anymore, which is why I dont like to buy obscurely branded oil products, because you never know if your buying from an idiot or not I really didnt read the article in depth but I think what they are saying is this: A 10w40 oil contains a larger molecular weight viscosity modifier, because it is larger is will oxidize(burn) easier. Therefore, if an engine is abused or over-heating the 10w40 oil will break down and thin before a 10w30 oil will. Car manufacturers are of course very concerned about warranty cost and therefore recomend the oil that will be more "idiot-proof" and still do the job. If you are a normal person who does not abuse your engine and changes your oil regularly 10w40 will do a better job of lubricating your engine as it will be thicker at normal engine operating temperature. I also spent 3 years in the mid 1990's working with alky units in oil refineries, anbody who believes that one major brand of oil or gasoline is better than another is fooling themselves, as they all use the same "pipeline" specs. Some do put in additives at the bulk terminal before shipment to retail outlets and occasionally a water problem sprouts up due to a faulty seal on a storage tank(they have floating lids), or due to a problem with the local retail outlets storage tank. A few brands of oil, Castrol for instance, put additional additives in, above and beyond the API standard package, which is the SAME for eveyone(I almost forgot, I am still a member of API - the American Petroleum Institute). These additives, Castor bean oil or whatever, may help under racing conditions or if the oil isnt changed, but I buy Wal Mart 10w40! I would like to know what weight the NASCAR guys use, I believe that it is 50w, according to what I know the brand of oil they use is totally dependant on the amount of money it takes to get the logo on the side of the car! If anyone knows any NASCAR people, it would be very interesting to find out what oil they use. My gut feeling tells me that if you said that they should use 10w30, they would get a real funny look on their face!

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thedaddycat
Aren't the older Briggs cast iron singles spec'ed for straight SAE 30? I'm pretty sure I read that when I went through the whole ST side of the site. Lighter oil was called for in winter.

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Al
Les, Question? In service school, they tell us not to use multigrade oil in the L head engines, but straight 30. The sheets do or did call out 30 Summer and 5w30 for cool/cold applications. What we were told is that multigrade doesn't stand up to the heat in the exhaust valve area of the cylinder due to the extreme temperatures in this area. That straight 30 is tougher under these conditions and doesn't "break down" at these temperatures. I know the first 7100, a 7117, I had as a dealer would take oil in unbeliveable quantities, I went to the engine manual and changed from 10/30 to recommended straight 30. End of oil consumption. I just traded for it last summer 21 years later. Junk KT now. With the new OHV engines, the cylinders are cooled much more evenly and the much of the heat goes up through the head and the oil temperatures are reduced significantly. With the advent of hydraulic lifters, [same as 350 chev] Kohler now recommends multigrade in the OHVS. Do you concur with this theory? Thanks Al Eden

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Les
Al, that sounds correct, the oil itself does not break down, but the viscosity modifier will, so a 30w will stay a 30w even at high and uneven temps. But if you run a 10w30 at very high temps, it might become a 10w, depending on how much time your operate between oil changes. How much oxygen is present is a big part of the equation too, this may vary with engine design. Moving hydrocarbons suddenly from a lower temperature to a higher temperature will "flash" the more volatile conponents. Another bad thing that could happen is residue from the multi-vis breakdown could become hard and coat moving parts. The other thing to remember is that today's lube oils are far superior to 20 years ago. All of your major oil refineries are now ISO 9000, which means that they all produce the exact same product, ISO comes from the Greek word meaning "the same." Also, additive packages are periodically improved, what are we at now SJ? When I blended back in 1981 we were at SE, so there have been five improved packages since then. So a number of factors could come into play. It is still my belief that the frequency of oil change is by far more important than what kind of oil you use. I still like 10w40(due to the high viscosity-ask the racing guys to know for sure), in order to keep viscosity at maximum for temperature. With your 7117 senario, one theory would be that the engine heat must have been destoying the viscosity modifier, why else would oil consumption go down with the change to straight weight. Another theory would be that the viscosity modifiers react to any change in temp, so the uneven heat of the engine causes the viscosity of the oil to change constantly, promoting oil consumption. Too many factors at work to know for sure. You did just give me an idea, on my Dad's Kubota, the oil pressure drops once the engine gets warmed up. I am using 15w40, maybe I can solve the problem by going to straight 30. This is a water cooled engine but it is thermo-siphon(no water pump) so there can be wider engine temp variation than in a normal water cooled engine. What do you think?

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Al
Les, I don't know, but would be interested in seeing if it makes a difference and how much. What does Kubota recommend? I would not expect to see the change with water cooling as with air cooling. Even thermo syphon, as it would still be below 212 degrees . In air cooled [L heads] I believe some areas of the cylinder near the exhaust valve pocket may be above 500 degrees. I would need to check on some notes I have. I don't know all that much about it, but I know I have had a lot of people stop their oil burning Kohlers by going to straight 30. Briggs seems to be more forgiving. Suspect it is related to the finning under the ex. valve pockets. On our race engines we always increased the rod and main clearances by a 1/2 thousand and the side clearances on the rods and thrust bearings on the main. Increased pin clearance 0002 and race pistons are forged and usually call for .002 to .004 more clearance than stock. Couple this with heavy oil, a hi voulume oil pump 8 to 10 quart finned oil pan and high releif settings and you [1] run the engine cooler and [2] move more of the heat to the pan where it is dissipated. The oil system is the major heat transfer means in these engines. I went to an oil seminar on 2 cycle oil about 4 years ago. The guy there said their refinery in Louisianna blended a very large majority of the 2 cycle oil sold in the US. He said that they made oil that should not be sold, but they didn't spec it they did it to the vendors specs. He said the oil they blended for Stihl at that time had more polymers and additives than for any other company they blended for. He said this was to make the oil stand up in the high temperatures in the 2 cycles and they blended oil for other manufacturers, and they paid to have oil blended nearly that good. He also said that they blended oil, that should not be sold. The new environmental requirements were forcing the 2 cycle mfrs to go to such lean fuel mixtures that the old 500 degree numbers were now being exceeded in the newer EPA engines and without the additives cylinder scoring would become much more common. One of the issues addressed was the fallacy of using outboard oil in mowers and trimmers. Outboard oil is low ash, to prevent ash buildup in the ports etc. These 2 cycles being water cooled do not exceed about 150-200 degree cylinder temperatures, high temperature performance is not an issue. Go to a Lawn Boy of this vintage and the cylinder temperatures run about 500 degrees. Ash in this engine is not a problem, as it burns and blows out. High temp performance is. Stihl a year ago changed their blender vendor a year ago. Supposedly their oil is even more improved now because the 2002 EPA requirements have forced all of the mfrs to new levels of lean burn, and oil is critical to stop cylinder scoring. Mc Culloch went bankrupt 3 years ago because they couldn't meet the EPA emmission requirements and could no longer sell their gasoline powered products in the US, only in foreign countries. These EPA requirements are forcing mfrs to really scratch. Stihl now makes a new 4 mix engine, a 4 cycle trimmer that burns mix fuel and is all position operation and meets the 2005 emission specs. Other companies are doing some unique things to survive also. Oil also seems to be a critcial issue in surviving the EPA. Have you been involved in any of this stuff? Any thoughts on this? Appreciate them. Al Eden

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Kent
I just added it to the Miscellaneous section of Links in the Resources, and put a link to this thread. The link to this thread shows up as Click Here to Discuss This Resource. The foot-draggin' Clubhouse Custodian...

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RenegadeJ
I have a son that works for NASCAR. Qualifing oil zero weight, real thin suff but they only run it for 2 laps. Also it is preheated before qualifing so it is really thin. For happy hour and practice 10W30. For the 500 mile races 20W50. All synthetic.

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