Single grade oil

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Not sure how to word this question, but here goes: is there any reason that a single-grade oil can't be as high in various standards as all the usual suspects of x-Wx varieties? I have never had to start my car at a lower temp than say 45-50°F. So I'm thinking a straight grade 30 winter (such as it is) and 40 would work. Is the prime reason for the existence of multi (synth) grades simply to allow for cold starts? I know there are conventional oils, but would like the other advantages of synthetics.
 
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Is the prime reason for the existence of multi (synth) grades simply to allow for cold starts?
Pretty much.

If you can find a SAE 30 at a reasonable price go for it but most places sell it by the quart or 1 gallon jug which might not work out depending on your sump size. I wouldn't go out of my way to find it or pay more than what i could get a 5/10w30 for.
 
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Choose the appropriate additive package for your application. For example Delo 100 SAE 40 is a solvent refined group 1, Delo 400 SAE 30 & 40
are high SAPS. For automotive use, Havoline 30 & 40 may be the ones for you.
 

Astro14

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Not sure how to word this question, but here goes: is there any reason that a single-grade oil can't be as high in various standards as all the usual suspects of x-Wx varieties? I have never had to start my car at a lower temp than say 45-50°F. So I'm thinking a straight grade 30 winter (such as it is) and 40 would work. Is the prime reason for the existence of multi (synth) grades simply to allow for cold starts? I know there are conventional oils, but would like the other advantages of synthetics.
It would work, as long as it meets the specs for your car. Many mono grades are not very good.
 

SR5

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OP, I've been asking myself the same questions.

Since you live in North America, you have access to some good monograde oils that also have up to date API SP rating. It's very unlikely that you will get more advanced specs on a monograde, such as Dexos, MB 229.5 or even ILSAC GF-6, as these specs require a fuel economy test or maybe cold starting test that is a monograde's weak spot. This cold start requirement is often indirect by only allowing certain viscosity grades (always multigrades) to hold the approval, e.g. Dexos1 allows 5W30 but not 10W30 no matter how good the 10W30 is.

But apart from starting in very cold climates (below freezing) and the associated warm up fuel economy hits, I think monogrades have a lot to offer. Such as no viscosity shear and very low Noack volatility.

As for synthetics, the more common cheaper synthetics multigrades are good, but commonly Group-III based. But Group-III base stock, even GTL, only comes in 2 cSt or 4 cSt or 6 cSt flavours. So to make a Group-III 5W30 with a KV100 of 10 cSt requires you to thicken it up with polymer viscosity index improvers (VII) and therefore must be a multigrade.

So monogrades only come as three types:
* Group-I, old school, bad oxidation stability and very bad cold characteristics. You don't want this.
* Group-II, viscosity index (VI) over 100, a modern mineral oil with better oxidation stability and better ability in the cold. A good choice. Often under tested (API SG because it's easy, and then sold as small engine oil). I think most of these could easily be SN, but there is no profit in doing more expensive tests on what is sold as a mower oil. Mag-1 make good SP rated SAE 30 and SAE 40 monogrades.
* Group-IV (PAO), fantastic but rare and expensive. A PAO SAE 30 could probably pass as a 10W30 monograde and I believe Amsoil has one.

More monograde talk here
 

SR5

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Dave-o from HPL will sell you a super high quality synthetic SAE 30 made on PAO & AN that tests out to be a 15W30

Thread here

 
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Dave-o from HPL will sell you a super high quality synthetic SAE 30 made on PAO & AN that tests out to be a 15W30

Thread here

There's 15w30s found in farm supply outlets and sold as multi functional oils that can be used in transmissions where an engine oil is specified, Allison TO-4, API CD and so on.
SAE 30 is often referred to as 20w30.
Edit; Group I mono-grades are not "old school" when used as intended.
 
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