Serious discussion about 10W syn for winter

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This will be a long post, but bear with me.

Will a 10W full-synthetic oil work perfectly fine in a relatively cold winter, where one would usually use a 5W-30?

On here these days, '10W' oils are getting a lot of attention b/c of there better shear stability and lower NOAK values, but many people would hesitate to use them in a relatively cold northern winter. But would they be just as good?

Many 10W synthetic oils have very low pour points and CCS values, so much so that they are almost a 5W oil. Many have speculated most are the same formula, just sightly tweaked. So I can't see there being any cranking problems down to even -30C with these oils.

Back in the early days of syns, the 1970's, most oils were 10W-40, including the new syns. Back then, one of the main observations made about the new synthetic oils was how much easier cars started in cold weather, even if a 10W-40 oil was used. So, a 10W full syn will always crank over much better than a 10W conventional.

Also, if you look at a lot of PDS's, many 10W-30 synthetic oils meet GM 6094M; which could only be met in a conventional oil in a 5W-30 due to required CCS values. So, a 10W-30 synthetic could be said to be equivalent to a 5W-30 conventional, which means it should be good down to -30C.

My Kia runs a lot smoother and consumes less oil on 10W-30, so I was thinking for this winter of using a top-shelf 10W-30 over the winter in it. BUT, I have had my last vehicle completely 'lock up' at an actual air temp of -29.5C with 10W-30 conventional in the sump. Our winter low temps around here are 'usually' in the -18C to -24C range; but we do have cold snaps where it can go to -29C to -32C. This is getting too cold for a 10W conventional, but would a 10W full-syn handle it okay?
 
when new a 10W "synthetic" could be good enough, but depending a 5W or even 0W would be better. refined CRUDE oils group III legally synthetic degrade with use as the additives get used up, real synthetic Group IV + V that require few of the additives that allow a refined mineral perform in colder + hotter weather. mineral oils thicken at a faster rate than synthesized true synthetics. 0W oils prolly need some real synthetic to meet that spec. a lot depends on how cold it gets!!
 
I've been using 10w40 synthetic in my 530i year round through Michigan winters and so far have not found any cold startup issues at all. My car sits in an unheated attached garage most times though.
 
Originally Posted By: Kamele0N
For the temperatures mentioned above I would rather use a 5w40 then....

I use RT6 5W40 in my tractor mostly for cold starts, but T5 10W30 is a "syn blend" and has nearly the same cold start specs.
In my cars in the same climate I always run a 5W20 or 5W30 in winter, sometimes synthetic but often PYB or something similar if its on sale. My cars seem to start fine in the rare -30C morning, so I'm going to stick with that.
 
Unless I'm missing something ... if two pour points are equal between a 0w and a 10w, then this simply means the one is a 0w at start up and the other is a 10w. If flow properties are fine for both in a given temp range, the 10w should offer better protection when driving the car till it is warmed up to operating temp since it is using a thicker viscosity. How much protection does a 0w weight really offer when driving a cold motor?
 
My father has used 10w30 synthetic in his V6 Jeep Liberty for years in winter without issue and we have had several winters hear in Western Massachusetts where it has reached -20F for an extended timeframe (Up to two weeks) and his Jeep "Left outside" always started right up. As a matter of fact last year against my advice he used up some simi synthetic 10w40 he had in the barn that was a few years old and his Jeep started right up without and strange noises. Back in the 80's I had a friend that ran a small repair shop specializing in Europen makes and all he used was Castrol GTX 20w50 for summer and 10w40 for winter and not one customer ever complained there BMW or Audi would not start.
 
Originally Posted By: Camprunner
My father has used 10w30 synthetic in his V6 Jeep Liberty for years in winter without issue and we have had several winters hear in Western Massachusetts where it has reached -20F for an extended timeframe (Up to two weeks) and his Jeep "Left outside" always started right up. As a matter of fact last year against my advice he used up some simi synthetic 10w40 he had in the barn that was a few years old and his Jeep started right up without and strange noises. Back in the 80's I had a friend that ran a small repair shop specializing in Europen makes and all he used was Castrol GTX 20w50 for summer and 10w40 for winter and not one customer ever complained there BMW or Audi would not start.

All my cars would probably start at -20F using 10W oil; they all have good batteries and properly functioning fuel, ignition and starting systems. But why would I want to do that? What benefit would I get?
 
I believe we over think this often. yes a 0w or 5w will flow better in the cold, but is there definitive proof that running a 10w will result in serious engine damage or failure?

I run my oils year round on the prairies. Its costly, time consuming and wasteful to swap oils out for the season. I do not garage my vehicles but they do get plugged in before use. I usually plug them in around the -15 or colder mark.

In my 1500 I ran PPPP 5w20 and in my Tb I run what ever group 3 synthetic is on sale, 5w30. I could get the oil cheap when on sale so it was not a big deal.

Fast forward to my 2017 3500 CTD. RT6 and the likes of that are expensive, over priced in my opinion. They are fine oils but are they really needed in my climate? I am not in the Yukon and I plug in when planning a trip.

I sourced out PetroCan 10w30 semi synthetic for it. It has decent cold weather properties, better than Citgo/Motomaster 10w30 semisynthetic and even RT5 10w30. It was 4.5$ a liter tax in locally. Am I worried that I will do irrevocable harm with this oil? Not in the least. I know a few people that run Powerstrokes, Cummins and Duramax's year round on the prairies with nothing more than conventional 15w40 and have had no issues for years.

yes this is anecdotal at best. I am planning to run some UOA on this truck. I just swapped out the factory fill and will look at this process later in the change index. Perhaps then I can put my money where my mouth is.
 
Originally Posted By: addyguy
Back in the early days of syns, the 1970's, most oils were 10W-40, including the new syns. Back then, one of the main observations made about the new synthetic oils was how much easier cars started in cold weather, even if a 10W-40 oil was used. So, a 10W full syn will always crank over much better than a 10W conventional.

Remember to not focus much on pour point. Also, watch the focus on an old GM specification. Note that SAE J300 has been tweaked over the years, whereas the GM specification was replaced and is obsolete. Whether something is actually meeting something or not isn't very easy to verify. If it's a 5w-30, generally speaking, it has to be labelled as such, and not as a 10w-30.

Historically, in my experience, it was always easier to start a well functioning carb in the winter over a fuel injected system, irrespective of what's in the sump. It's not just about cranking. Are you able to actually pump the oil?

Under most conditions, even in a Saskatchewan winter, a 10w-30 is certainly up to the task. But, if you wind up doing unaided starts in a stretch of -40, things can get dicey.

If you want to do some comparisons, take a look at Petro-Canada's data sheets. If I recall correctly, their 5w-30 conventional actually has slightly better CCS and/or MRV numbers than the 5w-30 synthetic. One may see that with their 10w-30, too, or find other examples from other oil companies. In fact, I would almost guarantee that an ILSAC 10w-30 conventional would have better cold numbers than, say, a 10w-30 synthetic blend HDEO.

How about an A5/B5 5w-30 for shear stability? Or, if you have access to a garage and a block heater (or an oil pan heater under the worst possible conditions), the 10w-30 would work each time without fail.
 
Conventional and synthetic oils have the same CSS and MRV test limits for any given grade, but I have noticed from looking at 5W30s that some (not all) synthetics will have CCS viscosities well below the limit (6600 mPa*s at -30C) while most conventionals seem to group fairly tightly just below that limit. Of course, if an oil is so thin at cold that it meets the 0W criteria, it has to be labeled as a 0WXX and not a 5WXX. Same thing with the grades you are looking at, any oil that really performs at the 5WXX CCS and MRV levels can't be labeled as a 10WXX.

You might well find a 10W30 synthetic that performs better at extreme cold than the 10W30 conventional that gave trouble before, but do you really want to take the risk? I've been doing OK parking outside on my frigid ski weekends with 5W30s that I knew were very good CCS performers for that grade (mostly M1s), but I would certainly switch to a 0W30 that had low NOACK loss and good LSPI resistance with no qualms. I'm not sure what the Subaru dealer put in my FXT for the first few changes, but I remember a couple of really shaky starts in the Whites with it...still started, but the car really seemed to be suffering!
 
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Does your car have a block heater? It's been my understanding that Canada vehicles (gas or diesel) typically come with them.

I started my Jeep in -25*F weather a few years ago with mineral 10w30 and it didn't sound good. It took a few seconds for the oil gauge to come up and my "check gauges!" chime went off. Would a mineral 5w30 made much of a difference? Who knows. Cars struggle in cold weather regardless. Your starter and battery come into effect. Get the most CCA's you can when battery shopping. I personally wouldn't make a regular habit of a 10w30 if I saw temperatures regularly that cold though. I would also invest in a block heater and a timer if I didn't have one.

I know you didn't ask, but I'll suggest it anyway. Have you considered a 0w40 or 5w40? Have you been able to try them and monitor consumption?
 
Blend pp 10w30 and 5w20 according to your desire.
Both have low noack and viscosity modifiers.

You do not list the brand of oil you are using and what noack it has. Most 10w30s noack will surprise you.
Dont assume low noack just because it is 10w30.

In my opinion qsid 10w30 is pretty close to being 5w30 as far as ccs and mrv are concerned.
 
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Originally Posted By: merconvvv
Blend pp 10w30 and 5w20 according to your desire.
Both have low noack and viscosity modifiers.

Why not just use an oil with an appropriate winter rating for the expected operating conditions?
 
Because blending gives you more control and ease in achieving your target at a lower price.

If you can find something that meets your target on the shelf already in a can at a price you like then thats good too.
 
Originally Posted By: merconvvv
Because blending gives you more control and ease in achieving your target at a lower price.

If you can find something that meets your target on the shelf already in a can at a price you like then thats good too.

Since the W rating isn't a viscosity how do you know what mixing does to the rating? In other words, you are saying you know what the results would be of the mixing?

For the number after the dash, yes. But you're saying you know what it does to the other number?
 
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