What's synthetic, conventional, semi-synthetic, and high mileage oil?

like how would u define all of them, also what is oil viscosity and do we need to change oil filters??? and if we do why do we?



Thanks I'm doing some car work and have to know these basicsWhat's synthetic, conventional, semi-synthetic, and high mileage oil?Synthetic- it is a high lubricant oil, it contains compounds that are artificially made through chemical processing unlike conventional oil which uses natural refinement of crude oil along with chemical purification.



Conventional oil-is oil that has been refined from crude oil, and is purfied to various viscocity levels, difference is that it is made through using more refinement and cleansing than having alot of chemical addatives, typically its more thick.



Semi-Synthetic- is basically a half in half between full synthetic and conventional. There is nothing real fancy involved other than it mixes the properties of a good acid and organic compound distiller, with the lubricating ability of a synthetic.



High-Mileage oil - this is typically an oil with various chemical additives made for keeping an engine clean. Not 100% sure on the chemical make up but, some high mileage oils have a detergent type compound in them intended to keep internally aged parts cleaned.



Synthetic is good for low mileage vehicles 0-130k-150k

After that, switch to semi-synthetic to about 200k

then go to standard.



Synthetic is a good lubricant but overtime your piston rings will ware naturally and will let organic and non-organic material into your engine.

Synthetic cannot distill a large amount of those materials.

Semi-Synthetic can distill more than synthetic and can also lubricate well.

Conventional is then the final alternative because it is a good lubricant and can distill very well.(good for vehicles that are used and you dont know the history of, but be consistent with oil brands)



You will want to change oil filters every oil change, reason is, as your oil goes through your engine, natural chemical reactions occur through prolonged heat and movement along with changes in temperature and moments of just sitting.

When your vehicle then sits overnight and cools you can get a very small amount of particle build up that will typically build up on the walls of your engine.

However, by running your vehicle consistently, those particles then go through your filter where they are caught.

For the sake of keeping your engine clean of those particles and ensuring your next oil change wont flush some of those particles out of your filter, and/or fill your filter up with more than it can take, you change your oil filter.

This way you can know that your vehicle is clean of any build up, and that by filling with new oil and a filter, whatever particles or build up were left over(because there will be some) they will get carried to the new filter and trapped till next oil change.



All oil viscocity is, is the lubrication process that the API does through testing. American Petroleum Institution.



For example; 5w-30. W stands for winter(some people call it weight, but its actually definition is winter) aka cold temperature, the viscocity is 5 at cool temperatures, the smaller the number the thinner the oil or lighter the viscocity. The 30 is the operating temperature viscocity.

So compare 5w-30 and 10w-30, in colder weather 5w-30 is better because it is thinner at cooler temperature so its not a heavy load on your engine and gets circulating quicker, at operating temperature is it the same as 10w-30 its just that small difference of the number in front(5w)



Now small engines also like 5w-30 because its not too thick and they run smoother from the start and as things warm up.

Put a thicker oil in there 10w-30 and not much changes but that slight thickness at the initial cold start of the vehicle.



So conclusion, there is a big old mathmatical equation for judging viscocity, and its easier just to remember what the different oil viscocity applications are.

(First and easiest way to find the proper oil viscocity for the vehicle is to look at the oil cap, it should tell you)



5w-30 and 10w-30 are standard weights, most vehicles will use them.

Up in colder climates, they will use a lighter viscocity, 5w-20 so the oil doesnt get too thick.

You usually dont want to go higher than 10w-30 for vehicles, although some you can.



Only brand oils ive witnessed that i do not like at all are, havoline, and quaker state. Any other oils are typically fine.



Hope this helps