Hello Phil Thanks for the email and tell Ron I appreciate the time it took him to reply, and the length of his explanation. He is busy running a business so I know he made some sacrifice, even if it means sleep! LOL
I will agree that all oils have improved over the years, they would have to. It would be stupid to not include advances in straight weights found in multi's. And some of Rons points about the merits of single visc oils I also agree with. I believe all engines should be broken in on single visc oils. The multi's do have too many additives that can end up burnt or not providing enough cushion lube to closely machined parts. We are also making some broad statements, because Oil Companies are known for changing oil and fuels to suit different climates AND different markets. The early 70's engines and late 60's engines are probably the best know around the world. Most other engines are measured against these engines. However, they are two full generations back from today's advanced engines. Those engines were kept at 160 to 165 degrees because water pump, radiator, coolant, and oil technology could not keep them cool if they ran hotter. This has a negative effect on fuel atomization and combustion chamber efficiency. Here we need things to be the hottest it can be without causing the fuel to flash ignite or become complete vapor prior to entering the chamber itself. Late 90's and engines of the 2000's are designed to attempt to maximize these parameters. They have thermostats that do not open until 195 degrees and are fully open between 205 and 210F. Then system hovers the temp between 205 and 220 relying on thermostat, and the coolant properties and pressure to prevent the coolant from boiling over. These modern multi oils also need over 140 degrees before they even begin to activate the additives within them. An engine maintained at or near 160 will never be able to benefit from a multi oil and will in fact do damage. However, this engine will also have a short life due to this low temp, as engineers of late have found, due to the fact that the metal is "cold" too much of the time effecting everything from the fuel atomization to the strength of the crank. Mixtures will have to be richer, which causes more cylinder wash, shortens any oil's life. The crank is weaker possibly as much as by half, due to the fact that areas not flexing are around engine temp, while areas flexing and working are going up in temp, with a more brittle metal. I have always been told by those that know that metals break faster in the winter than summer. A quick check of the temp ranges of operation for single vs multi will reveal that there is no way a single visc oil can run well in a modern engine because it cannot adapt from 0 degrees in winter to operation internally of 250 degrees, and then switch to temps of 70 degrees to 130 degrees outside driving underhood temps to 400 degrees and internal temps back up to 250 degrees. And all this with an engine that is designed to begin driving after only a warmup of 30 seconds. Single visc oils can be used regularly if temps are paid attention to and the weight adjusted accordingly. Most people do not go to the trouble hence the need to develop oils that adjust for you. My fear is that since alot of our readers do not know, they will not know the difference and that could cause an engine failure. I agree that lack of such know how should be a screening tool for not allowing these people into the air, but somehow they make it up there any how. More and more builders are using engine combinations with modern settings, clearances and metals and need these multi's to survive. A case in point is the use of the Geo Metro 3 and 4 cylinder engines. These engines MUST use the thinner 10w30 or 5w30 oils or their valve train will fail very soon after they are put into use, causing catastrophic failure. Their oil return holes in the heads do not provide a large enough orifice to allow a thicker oil to circulate, common among most all of the overhead cam engines. Depending on the version of the vortec engine they may also have to use a multi oil to be properly maintained. Single weight oils tend to be correct for too narrow of the temp range, making the possible extremes go outside their design range and begin breakdown. Especially in cases of engine sitting and getting part time use the multi's are particularly necessary due to the fact that when the oil was added it may have been summer but now is winter and a single visc will not be able to handle the range of temps and may not pump initially when started. Multi's will thin due to additives and circulate immediately. Even looking at the popular Corvair motor, the temps it will operate in is outside air maybe 60 degrees and then will be working hard climbing and soaring to head temps of over 300 degrees. Single visc oils cannt adjust for this wide variation in temps, so either you have one that handles the low temp part, or the high temp, but not both. If singles could do this, there would be no need for the multi's any more. If VW's are supposed to operate similar to the Corvair, then you can see a single used after breakin will sacrifice durability and longevity. Colin N96TA > > From: "Phil Matheson" <mathes...@dodo.com.au> > Date: 2006/06/24 Sat PM 10:30:26 EDT > To: "KRnet" <kr...@mylist.net> > Subject: Re: KR> oils and stuff > > Colin Wrote :Just for the record I will say this is foolish and potentially > catastrophic > ---------------------------------------------------- > This is a reply from Ron Slender VW Engines, > > > Phill, > I would like Colin to have a look at the article on oils I sent you. Agreed > that the refining processes are much more advanced from years gone by > however > that applies to all viscosities of oil including single viscosity. > The reality is that single viscosity oils handle a higher heat range better > than a multigrade. > Additionally a multigrade was primarily developed so that an auto engine > could start at a relatively cold condition and gradually reach operating > temperature which in most vehicles is around 160/180 degrees. > > Multigrade oils have a lot of polymers and additives to give the oil the > viscosity but do nothing to help lubrication, in fact they break down in > high temp conditions. > > Single viscosity can handle the higher temps better. Additionally the oil > tends to "cling " better for cold starts much like the sticky Shell oil used > for aircraft because not all aircraft are used every day. Some oils can > drain off providing high friction starts until oil pressure is there. > > I believe that you have to know a lot about the environment the aircraft is > operating in and recommend the oil according to the application. > Additionally Phil's engine is basically new and oils that have friction > modifiers and high range of viscosity will effect the running in of that > engine. > After Phill has reached 50 hours then he make look at alternative oil > options. > However we have used straight 30 ; 40 ; & even 50 (very hot conditions) and > the Shell oil for aircraft for air cooled engines. > We do not use multigrade because of the fear that friction modifiers are > often used in these types of oils which inhibit running in. > > Colin, your article on HP and how it effects speed was very good > demonstrating that hotting up an engine can only increase overall speed > marginally. Without going into elaborate equations the power difference was > 35 HP and the actual Torque increase using 2500 rpm as a constant the extra > Torque created by adding an extra 35 HP was only 63 ft lbs and that was at > full power. > Same goes for our gear drive engines. We have the Torque that say a 100 hp > creates at 4200 , the reduction drive multiplies the Torque by the ratio on > top of this. As long as a respectable size prop can be used to benefit from > the extra Torque gain then the advantages of a reduction drive is clear. > Because of the extra torque gain take off roll is reduced particularly when > loaded, climb out is great and cruise is probably achieved at a lower > throttle setting because of the prop diameter and available torque. > A reduction drive will not necessarily provide a higher speed because this > is a character of the aircrafts drag as Colin explains. > > The propeller has not even been discussed. Fixed pitch is a compromise, that > we all except as being the norm because anything else is expensive. > Why not fit a suitable in flight adjustable propeller then you will see some > performance. > Trouble is the cost of one of those, but ...I would rather spend money in > that direction then spend lots of $`s trying to squeeze out a few extra HP > out of an engine for very little gain. > > Not quite with you on oil Colin but I did like your thoughts on HP and drag. > > Ron Slender > > > > > > > > Phillip Matheson > 0408665880 (cell) > VHPKR > Australia. > mathes...@dodo.com.au > NEW WEB PAGE > www.philskr2.50megs.com > > http://www.vw-engines.com/ > OLD WEB PAGE > http://mywebpage.netscape.com/flyingkrphil/VHPKR.html > > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html >
