I'm confused by your statements. In the first sentence you ask whether synthetic blended oil has all of the advantages you are looking for in full synthetic and in the second sentence you answer your question by stating that full synthetics have the benefits you are looking for.
The answer to your question is to read your owners manual and maintenance schedule. Choose an oil that meets all of the required specifications. API, ILLSAC, ACEA and/or any manufacturers proprietary specifications, pay strict attention. A good conventional oil of the proper spec beats a synthetic that doesn't meet spec.
No, its just mineral oil with some 'synthetic' additives. Thats why it costs a lot less.
Full synthetic will last longer than mineral and giver better cold protection, but cheap new oil will always be better than expensive old oil, so how often you change it counts for more.
A few months ago. I bought Pennxoil Max Life 100% synthetic for 99 cents a quart, after rebate and coupon, at Pep Boys. My previouis purchase for this oil cost 6 cents a quart, after Pep Boys and Pennzoil rebates. That's why I don't bother with semi-synthetics.
Some auto parts chains have coupons in their Sunday newspaper ads that don't appear in their regular ads, and sometimes you can find printable coupons at their websites.
Questions to all:
Which is better:
a) using synthetic blend and leaving it in for 7500 miles, or b) using regular oil and changing it twice as often?
How much synthetic is in synthetic blend?
How much synthetic is in regular oil? I read that some synthetic has to be mixed in to meet current quality standards.
You forgot one important question - what exactly is synthetic oil? Is it oil that is a highly refined crude oil (group III oils), or oil built from molecules created from the ground up? Until a few years ago, I only considered the latter "synthetic" oil. These days everybody sell highly refined Group III oils as "synthetic." And by everybody, I mean everybody, except maybe Mobil. Even the "First Name in Synthetics" hucksters (Amsoil) sell highly refined group III oils and call them synthetic (the XL product line). So I am not sure you can answer any of your other questions until you decide exactly what you mean when you say synthetic oil.
I would go with b) because although synthetic will perform better for a bit longer, it won't remove all those tiny bits of metal that make it black. Your magnetic sump plug has the same effect on both oils (ie not much).
You can thank Castrol for that. Mobil sued when Castrol started calling Syntec synthetic oil and lost. The FTC allows the use of the term "synthetic" for highly refined group 3 oils.
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