Hi all, which is better for a 3.8 v6 mitsubishi engine, put synthetic blend oil and change the oil every 4k miles, or put full synthetic oil and change it every 8k miles? Of course both with the viscosity recommended by mitsubishi. Thanks
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Just know that "synthetic blend" does not mean 50% synthetic oil in the mixture.
It could be 50%, or it could be 5%. The oil companies refuse to say.
At the end of the bottling line, a guy opens the container and says the word "synthetic" over the opening.
Exactly! It would stand up in court too. 
Agreed. I find it interesting that the only synthetic blend motor oil I have found that is Dexos approved is Pennzoil Gold. This oil must have a large amount of synthetic oil in it to be Dexos approved and still be classified as synthetic blend.
"synthetic oil" is meaningless marketing jingo. There is no agreed upon standard called "synthetic" that you can measure an oil up to and say, "yup. This is synthetic oil". It's only a word they put on the bottle. It's just like vitamins, supplements, "organic" food. It's not regulated and what's in the bottle might have nothing to do with what's on the label.
What you CAN rely on is oil classification standards.
- American Petroleum Institute (API) SN, SN+ etc.
- International Lubricant Standardization and Approval Committee (ILSAC) GF-5, GF-6, GF-6B etc.
- Dexos 1, 2 etc.
Read the owner's manual to find out what the manufacturer has indicated that your car needs. Read the label on the oil bottle and see these organizations have given their stamp of approval that the product meets the specifications that you car needs.
Wikipedia:
In 1998 the "new" definition of 'synthetic oil' became much looser to downgrade their process to the more affordable process. The result is a hydrocracked, hydroisomerized conventional oil.
Thanks
MM Joe has the definitive answer on this. It's sort of like Balance of Nature supplements. If you really want to spend $89 for two bottles of red and green colored sawdust in Chinese manufactured gel caps, have at it. The service ratings on the back of the container is what really counts when it comes to oil.
Full Synthetic with an oil change interval of 1 year/5k miles, whichever comes first. That's the best choice. Don't stretch your oil change intervals or you'll wind up being your own worst enemy.
I will, thanks
I would get the full synthetic. It isn't really that big of a difference in price but as carlos says you don't know the exact percentage of synthetic oil if you get a blend. 8k mile oil changes seems a little long to me even for a synthetic, but it isn't outrageous. I have always done 5k with full synthetic, but thats just me.
Ok
I would use full synthetic if you can. Really as long as its getting changed every 40000 miles along with the filter its probably fine with either. I like to use the Havoline 5w-30 pro ds full synthetic. Its really good oil for the money. Its what I have always used.
Thanks!