NTC garage is an enthusiasts page
NTC garage is a group of dedicated enthusiasts specialising in modified cars.
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Hi all, Thought I would give out part of a Basic Tech help guide I am currently putting together. This is for all the people out there who are just starting to do their own maintenance and are unsure on what to use and why. Oils, Engines and Maintenance. After many years of being a mechanic and being involved with a younger motorsport orientated community, I feel I need to share some basic technical knowledge I have gathered over time regarding oils, engines and basic diagnostic on engines. Firstly, I am no expert. I use experience and the magics of science and logic to work these out. Issue number one being a technical understanding of how to pick an engine oil for your car, and when it is ok to use a different weight oil or NOT. Now, most people on the planet even with a rebuilt engine run a factory specification on their main and conrod bearing clearances. So approaching this in a simple way, the manufacturer chooses an oil weight that is suited to the bearing tolerances built into the engine. Now most of the time these tolerances are in a thousandth of an inch..literally 0.01mm specifications. So imagine this as a very small hole that you must get oil into to prevent the sides touching each other. Too thick and it wont go into the hole, too thin and the sides will push together and touch, causing wear. Now in the life of a motor, from new through to unservicable, the wear tolerance is usually quite insignificant. eg. 3 thou. If the bearings wear this much, they will usually fail and compromise the motor. Now think about that.. 3-4 thou at the absolute most. Thus using this, given the factory clearances are similar sizes 2-3 thou...you can see how using a oil that is 20-60w in an engine that is designed for 10-30w or even 5-30w, is going to increase wear as the oil will not be able to service the bearings correctly. This brings me to the ever so common, "it is noisy/leaking/smokey so just put a thicker oil in" method of mechanics that most seem to use. Based upon technical evidence you can see how this just wont work. Thicker oil may prevent some other out of service part from being faulty it will also just result in wearing your engine bearings and piston rings prematurely. This is also many peoples approach when the vehicle "Runs Hot" or over heats from hard driving. Now the modern oil weighting system specifies the oils performance at correct usage temperatures. If it goes too much outside these parameters , it will most likely cease working as a lubricant correctly and begin to deteriorate rapidly. Once again, itll create a situation where; when cold, the motor will not be lubricating the bearings and rings correctly and likewise when hot, doing the exact same thing. So from the above, the common sense method for picking an oil for your engine is to use what is specified by the original manufacturer. More than likely it will be the best oil for the longevity of your motor. There is one exception to this, when people build a motor with different clearances to the factory specifications. In which case oil weight will require some technical working out. That's all for this week, more to come such as engine blow by, cooling systems and Trans oils. Hope it helps... Cheers. - Beau NTC