I was talking to a friend the other day, and as he is an engineer for a major Petroleum company, the age old debate over Synthetic vs mineral oil came up. After a period of discussion, he said he would get back to me with all the relevent information. Well here it is (he is pro synthetic, and now I am too) Extended oil drain periods Better wear protection and therefore extended engine life Most synthetics give better MPG They flow better when cold and are more thermally stable when hot Esters are surface-active meaning a thin layer of oil on the surfaces at all times If you want to know the reasons why then please read on but, warning - Long Post! Stable Basestocks Synthetic oils are designed from pure, uniform synthetic basestocks, they contain no contaminants or unstable molecules which are prone to thermal and oxidative break down. Because of their uniform molecular structure, synthetic lubricants operate with less internal and external friction than petroleum oils which have a non-uniform molecular structure. The result is better heat control, and less heat means less stress to the lubricant. Higher Percentage of Basestock Synthetic oils contain a higher percentage of lubricant basestock than petroleum oils do. This is because multi-viscosity oils need a great deal of pour point depressant and viscosity improvers to operate as a multigrade. The basestocks actually do most of the lubricating. More basestocks mean a longer oil life. Additives Used Up More Slowly Petroleum basestocks are much more prone to oxidation than synthetic oils. Oxidation inhibitors are needed in greater quantities in petroleum oils as they are used up more quickly. Synthetic oils do oxidize, but at a much slower rate therefore, oxidation inhibiting additives are used up more slowly. Synthetic oils provide for better ring seal than petroleum oils do. This minimizes blow-by and reduces contamination by combustion by-products. As a result, corrosion inhibiting additives have less work to do and will last much longer in a synthetic oil. Excellent Heat Tolerance Synthetics are simply more tolerant to extreme heat than petroleum oils are. When heat builds up within an engine, petroleum oils quickly begin to burn off. They are more volatile. The lighter molecules within petroleum oils turn to gas and what's left are the large molecules that are harder to pump. Synthetics have far more resistance as they are more thermally stable to begin with and can take higher temperatures for longer periods without losing viscosity. Heat Reduction One of the major factors affecting engine life is component wear and/or failure, which is often the result of high temperature operation. The uniformly smooth molecular structure of synthetic oils gives them a much lower coefficient friction (they slip more easily over one another causing less friction) than petroleum oils. Less friction means less heat and heat is a major contributor to engine component wear and failure, synthetic oils significantly reduce these two detrimental effects. Since each molecule in a synthetic oil is of uniform size, each is equally likely to touch a component surface at any given time, thus moving a certain amount of heat into the oil stream and away from the component. This makes synthetic oils far superior heat transfer agents than conventional petroleum oils. Greater Film Strength Petroleum motor oils have very low film strength in comparison to synthetics. The film strength of a lubricant refers to it's ability to maintain a film of lubricant between two objects when extreme pressure and heat are applied. Synthetic oils will typically have a film strength of 5 to 10 times higher than petroleum oils of comparable viscosity. Even though heavier weight oils typically have higher film strength than lighter weight oils, an sae 30 or 40 synthetic will typically have a higher film strength than an sae 50 or sae 60 petroleum oil. A lighter grade synthetic can still maintain proper lubricity and reduce the chance of metal to metal contact. This means that you can use oils that provide far better fuel efficiency and cold weather protection without sacrificing engine protection under high temperature, high load conditions. Obviously, this is a big plus, because you can greatly reduce both cold temperature start-up wear and high temperature/high load engine wear using a low viscosity oil. Engine Deposit Reduction Petroleum oils tend to leave sludge, varnish and deposits behind after thermal and oxidative break down. They're better than they used to be, but it still occurs. Deposit build-up leads to a significant reduction in engine performance and engine life as well as increasing the chance of costly repairs. Synthetic oils have far superior thermal and oxidative stability and they leave engines virtually varnish, deposit and sludge-free. Better Cold Temperature Fluidity Synthetic oils do not contain the paraffins or other waxes which dramatically thicken petroleum oils during cold weather. As a result, they tend to flow much better during cold temperature starts and begin lubricating an engine almost immediately. This leads to significant engine wear reduction, and, therefore, longer engine life. Improved Fuel Economy Because of their uniform molecular structure, synthetic oils are tremendous friction reducers. Less friction leads to increased fuel economy and improved engine performance. This means that more energy released from the combustion process can be transferred directly to the wheels due to the lower friction. Acceleration is more responsive and more powerful, using less fuel in the process. In a petroleum oil, lighter molecules tend to boil off easily, leaving behind much heavier molecules which are difficult to pump. The engine loses more energy pumping these heavy molecules than if it were pumping lighter ones. Since synthetic oils have more uniform molecules, fewer of these molecules tend to boil off and when they do, the molecules which are left are of the same size and pumpability is not affected. Synthetics are better and in many ways, they are basically better by design as they are created by chemists in laboratories for a specific purpose. If you have made it down to here, congratulations :thumbsup: Regards GT
I have always been a supporter for synthetic but that post is the last word Well done mate, great post. I agree with Ron, when do we get synthetic fuel but with synthetic oil prices compared to petroleum based oils, that could be quite scary for the hip pocket. I was originally using the Valvoline full synthetic but I now use Penzoil Syntheitc 5-50W. $39.99 for 5 litres from Supergeek Auto.
good call, Mobil1 15w-50 is for me, I ran a few reduced drain time changes on 5w-50 to clean it out, and now 15w-50 is the go for me, We even run the Jet boat on it now, the oil analysis has come back very pleasing, Mobil1 Page :thumbsup:
Anyone Else Had Probs With Synthetic Oils I have found in a few older cars that I have worked on that sythetic oils tend to create excessive lifter noise and leak through some of the seals. Mabee just happens to me? All the points in your posts sounds technically correct, but has anyone really noticed greater fuel efficiency in their cars from sythetic oils, and would you leave your Z any longer than 5,000 - 10,000 ks max to change oil anyway. Just though I'd see if anyone else can see justification in the much higher price of synthetics - obviously they do :thumbsup:
the materials used fo seals in old cars are not suitable for synthetic oil. I don't know how old though :wacko: I'd guess anything 80's on would be fine with synthetic
made it to point X, gt ..!!! .. good and interesting post .. i had understood that a synthetic oil was the way to go or, in the case of munz's query, a syn/mineral mix for older vehicles .. BUT that earlier oil changes were desirable if using synthetic ...????:unsure::unsure::unsure:
I sitll cant find that 15 - 50 Mobil1 full synth. mabye I'll have To get you to get me some and then You can bring it to a cruise or some thing. Haha
The problem is probably not synthetic vs mineral, It's probably not the fact that the oil is synthetic, it's more that most synthetic and modern oils have a lower viscosity rating when cold, which is lower than what the older engines are designed to work on. Old design engines prefer around a 25W cold viscosity. Stick a modern 0W or 5W in them, and they will have noisy lifters, and leak more. Castrol R Synthetic 10W60 for my Zed, and a few older toys.
I have been using Mobile Super S 10W-40 since ownership... but just recently started suffering from lifter tick. Might be time for something a little thicker. Any suggestions?
Mobil Delvac 1 Synthetic A lot of the Porsche V8 (928) owners swung over to Mobil Delvac. It's similar to Mobil 1 but a much sexier black package and not as easy to find everywhere. A porsche owners website similar to this had a very experienced oil guru who was right up on this. He operates both heavy vehicle fleets, a Subaru, BMW Z3 and a 928 Porsche. Price is about $50-60 per 5 litres and we used to buy in a small group to spilt up some min package buys. It was very slippery stuff and you could feel the difference with a sumpful of this. I've used Mobil 1 in some very garden variety and high performance cars since the early 90s. It does the job but the packaging (and perhaps the oil) is not the most exciting. Any 300ZX Delvac users? www.mobildelvac.com John :zlove:
Yep Draco yes it is sold as a heavy duty oil for diesels. But works fine in petrol engines. When I have the spare time I'll copy over some of the Delvac 1 guru stuff from the Porsche group website. I'm not suggesting anyone rush out and buy this. What works well in high performance V8 may not suit a turbo V6. John :zlove:
The only bad thing I can say about synthetics.... ...is it doesn't cling to metal as well as mineral oil. Not a problem for a daily driver though.
