Engine oil choice

[Brucebo]

I've switched all my cars to Mobile 1 High Mileage synthetic.

-B

[tjts1]

I took some automotive engineering courses in college and my professor was on the lubricants committee of the SAE and liked to teach a lot on oils.
The specs for oil are performance based and different manufacturers use different additive packages to meet the specs, and some additive packages are not compatible. I had a friend who mixed oils in a low mileage pickup and then proceeded to pull a trailer over a pass in southern Oregon. He lost the engine in less than 100 miles.
If you drain your oil with the engine warm, parked on a level surface, and let it drain for 5 minutes, you should have less than 1/8 quart left in the engine. It is not good to change brands with each oil change. Unless you have a reason to change, stick with the same brand.

Maybe there was something else wrong with your buddy's truck. I can't remember how many times I mixed oils with whatever I had left over. Different brands, viscosities, synthetics with conventional oils, etc. Never had a single problem.

[waynej]

It's very irresponsible to recommend that others do something that could damage their cars just because you got away with it.
I am not saying it will destroy all engines instantly.In the example I gave he was operating at full power for an extended period of time. This would only occur if you were pulling your boat etc. up a long hill. With the relatively gentle driving most of us do we would not loose an engine, but we would definitely shorten it's life.

[tjts1]

It's very irresponsible to recommend that others do something that could damage their cars just because you got away with it.
I am not saying it will destroy all engines instantly.In the example I gave he was operating at full power for an extended period of time. This would only occur if you were pulling your boat etc. up a long hill. With the relatively gentle driving most of us do we would not loose an engine, but we would definitely shorten it's life.

I'm not recommending that everybody should start mixing oils for fun. But the claim that mixing oil is somehow dangerous for the engine is . Even under severe conditions like high load at high temps for long periods of times, it is completely irrelevant. Some people mix oils because they are trying to combine the qualities of multiple oils. Head over to BITOG and search out some of the of threads where people mixed oils with oil analysis results. I dare you to find a single engine failure or case of accelerated wear. As long as both oils meet the specifications of your engine and temperature you can mix any 2 or 10 oils you want.
I've had 4 volvos (240, 960, 850, S40), , 1 mercedes, 1 bmw, 1 dodge neon, and and a ratty old chevy wagon under my care in the last 5 years. All had various mixed oils in the sump at one time or another. The volvos, bmw and mercedes received mostly synthetic oil, the dodge and chevy got whatever was on sale at any given time. Both the dodge and the chevy drove under their own power to the junk yard at 170k and 210k miles after accidents. All passed California smog check every time.
cheers
Justin

[ykfc]

you said that the castrol semi synth was working well in your car...so why change ?

Answer to your query: Instead of going back and pay the old workshop to do the job, I am going to buy and change the oil myself.

I am now satisfied with how to choose oil after visiting the websites of different oil suppliers (such as Castrol or Shell). Their websites allow me to enter the vehicle model and they will give me their recommendations.

I must only decide now whether it is any big deal to mix 300 ml oil of another brand to 5000ml.

[mosearch]

I must only decide now whether it is any big deal to mix 300 ml oil of another brand to 5000ml.

It is no problem at all to mix that small residual amount with your new brand oil.

[Nathandu]

I would be more carefull when selecting oil. A friend of mine drives a 1989/90 Toyota MR2. Believe it or not somehow this car won't accept syntech oil at all. He put syntech oil first time, engine behaved very strange. He then drained it out, put back regular 10w30, engine worked fine. We could not believe it. So he drained regular oil out and put syntech oil in again, bad thing happened again. From then he only used regular oil. Well, I think oil is somehow quite important. Something to share with you guys.

Good luck
Nathan

[mosearch]

somehow this car won't accept syntech oil at all. We could not believe it.

Neither can I...