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Cap-in ID
12-23-2003 10:36:55
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Re: 20W oil in reply to RandyinWNY, 12-23-2003 05:29:58
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Randy - This may take you awhile to read but stay with me - When I first became involved with internal combustion engines what was available and what was used was single viscosity non-detergent oil. Then came detergent oils. Many resisted using them and for the usual reasons: "if it ain't broke don't fix it", "who wants all that crap floating around in their engines" etc., etc, and yes, some valid criticism based mostly on incorrect usage of the oils such as putting them in a high time, internally dirty engine. Over time mechanics found that when using detergent oils the engines were much cleaner and gave more hours of service so detergent oil became the accepted standard. Then came multiple viscosity oils. Now this really raised a controversy i.e. "who's going to put that thin oil in a hard working engine", "not thick enough to do the job", "it'll just let the engine wear out faster", etc. In the racing fraternity we were slow to change because our engines were used differently. We always throughly warmed up our engines before putting them to work and so the need was not as apparent. Engines are designed and the clearences set to operate at a given temperature with a given thickness of cushioning and wear reducing oil film. This oil film is maintained by the designed oil pressure. Too much oil pressure = wasted horsepower (think of how you can hear your engine rpm drop when you engage the hydraulic system. Too lower an oil pressure = insufficient oil flow to provide the necessary amount of cushion and lubrication. Think of how the operating oil pressure drops over time as the engine becomes worn and clearances increase. This is why using heavier oil in a worn engine will tend to increase oil pressure and prolong engine life. Most importantly, it is necessary to understand that most of the wear that occurs in an engine occurs WHEN THE ENGINE IS FIRST STARTED and before it is up to operating temperature. Comparatively very little of the wear occurs after everything is up to normal operating temps, design clearences have been attained, and the designed lubrication is being provided. In reciprocating internal combustion commercial aircraft engines this problem is partially overcome by having independently driven lube oil pumps that are switched on and operating oil pressure attained before firing up the engine. In heavy equipment diesel engines we crank the engine until oil pressure has developed before we add in a fuel setting to allow the engine to begin firing. Now, how does all this apply to MultiVis engine oil ?? Well, here's what is still commonly not well understood about multiviscosity engine oils. They provide the best of both worlds. They are thin and flow easily when cold, providing better start-up lubrication and are thick and meet the designed lubrication factors when the engine is at normal operation temps. A standard single weight engine oil is a given viscosity when cold and as that oil warms up the oil becomes thinner. A mulitviscosity engine oil is at the specified oil weight when cold (the low figure) and actually thickens as it warms up (to the specified high figure) i.e. 20W-40W multiVis is the thickness of 20W when cold and is the thickness of 40W when at normal operating temps. The wonders of modern chemistry ! ! Like so many things in this day and age, modern oil technology is vastly superior to what we used to have and, if the correct range is choosen, will better meet the needs of any engine. This is one of the main reasons it is now commonplace to get 200,000 miles on an engine and have it still perform well. When I started out playing with "real" engines most of them didn't last more than 60 or 70 thousand miles. In fact, up until about 1950 the Volkswagen factory would give a gold watch to any Volkswagen owner that attained the magical figure of 100,000 kilometers without overhaul. (and they were very well made machines). Unfortunately my first one was a 1951 so I never got my gold watch. It was one year newer than my current 8N, wish I still had it. I pulled it down at 160 thou.+ found virtually no wear, touched up the valves, put it back together and gave it to my daughter. But I digress, what I'm saying is, use a good quality 10-30 or 20-30 or 20-40 high detergent oil year round (low end depending on how cold it gets in your area and high end depends on how worn your engine is). Your engine will last longer, perform better, and start better. I would suggest that when making the change-over to detergent oil you start by "flushing" the engine. Put on a new filter, put in some high detergent oil, run the tractor a few hours at normal temps (say 4 or 5 hrs) then drain and replace both the oil and filter. By the way, never mix multi-vis with straight oil. The problem Bruce VA exprienced of lower oil pressure was because the chemical additives in the 1 qt of multi-vis he mixed with the 5 qts of single weight were insufficient in quantity to produce the thickening effect, so all he ended up with was 6 qts of thinner oil -- hence the lower oil pressure.
Happy Tractoring -- Cap --
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