5w30 vs 10w30 in the summertime

Patman

Staff member
Messages
21,988
Location
Oakville, Ontario
I remember when GM and all the other major carmakers made the switch to recommending 5w30, they claimed it was also beneficial in the summertime since the oil would flow faster to the top end of the engine. But I have always felt that 10w30 will flow just as fast as 5w30 in the hot weather, especially since their viscosities at 40c are usually very similar, only a few percentage points off in most cases. I've always felt 10w30 to be the better choice for summer, since it uses less VII and generally speaking the 10w30 version of a particular brand shows better HTHS, Noack and flashpoint numbers than it's 5w30 version. Thoughts?
 
Messages
237
Location
Augusta, Ga
This is a question that I'm very interested in. I've been considering switching to M1 10w30 this spring from M1 5w30. It can get brutally hot here in Georgia and I was thinking that using a 10w30 during the hot months would be a good idea.
 

tai

Messages
54
Location
Austin, TX
I agree that 10w-30 will be better in the Summer for all the reasons you listed, Patman. GM's recommendation, like other manufacturers, probably has more to do with improving fleet fuel efficiency ratings (like recommending 5w-20), though for most people with their conservative habit of doing 3k mile oil changes, 5w-30 should be no problem. In my high-revving and turbo cars, I'd rather use 10w-30 than 5w-30.
 
Messages
2,230
Location
SE MI
For the summer 10W-30 is fine, but what about in the winter? Is there a big enough difference in the cold temp viscosity to warrant the NEED for 5W-30 over 10W-30 in an OHC engine in the winter?
 
Messages
951
Location
Loveland, Colorado
I agree, sort of. You don't qualify the oil, but knowing your preferences, I'm assuming you're theorizing about full syn. That being the case, why are we not considering a quality 0W-30 year-round? Something like the M1 is thinner at 40C than the 10W-30 but thicker than either the 5W or 10W at 100C. A few 0W-30s are ACEA A3 rated (but not many here in NA), which would also make them ideal for squeezing as much fuel economy out of a turbo as possible. Of course, this is kind of a moot point, right? Any PAO full syn 10W-30 will flow fantastic all year long, thereby negating the need for even considering a 5W or 0W for cold-flow characteristics. Now if, in fact, you're suggesting mineral oils, then I'd agree that 10W-30 is better for all temps above freezing. But you're not really suggesting that, are you?
 

Patman

Staff member
Thread starter
Messages
21,988
Location
Oakville, Ontario
quote:
Originally posted by metroplex: For the summer 10W-30 is fine, but what about in the winter? Is there a big enough difference in the cold temp viscosity to warrant the NEED for 5W-30 over 10W-30 in an OHC engine in the winter?
I used to think that a real good 10w30 could be used in the winter, and I still do, however after going through such a cold winter here, I do believe a 5w30/5w40/0w30/0w40 would be a little bit better.
 

Patman

Staff member
Thread starter
Messages
21,988
Location
Oakville, Ontario
quote:
Originally posted by Greg Netzner: I agree, sort of. You don't qualify the oil, but knowing your preferences, I'm assuming you're theorizing about full syn. That being the case, why are we not considering a quality 0W-30 year-round? Something like the M1 is thinner at 40C than the 10W-30 but thicker than either the 5W or 10W at 100C. A few 0W-30s are ACEA A3 rated (but not many here in NA), which would also make them ideal for squeezing as much fuel economy out of a turbo as possible.
This is why I find that german 0w30 Syntec so interesting. It's got better cold weather specs than anything I've ever seen come off the shelves of Walmart, and has an incredibly good HTHS for a 30wt oil. I'll be running this oil in my sister's car through the summer, so we'll see how it handles that. I'm sure it'll pass with flying colors.
 
Messages
605
Location
Mississauga, Ontario
How much is the German 0w30 Syntec at Walmart Pat? If we're talking synthetic I'd say for all but the most coldest climates you could run 10w30 all year long safely. In my case due to the characteristics of my engine I'll be using the M1 0w40 in the summer, and M1 10w30 in the winter.
 
Messages
4,799
Location
Lakeville, MN
I think a lot of this has to do with the quality of the oil you are using. Old school thought always said use the oil with the least difference in numbers (ie: 10w30 instead of 5w30, etc...) for the temperature range you expected. VII's were the weak link in the packages and so the oil with a bigger spread tended to shear back to a thinner oil over time. As time has gone on, technology has adavanced, and oils have come along for the ride. Less VII or better VII can mean the oil holds up better over time. On my beater, an '89 Chevy Cavalier, I actually can tell the difference between the 5w30 and 10w30 oil depending on outside temps. Under cold weather, the 10w30 causes hard starting at anything under about 10 F. It won't idle and takes a while to smooth out. 5w30 fixes that nicely, and it doesn't grumble very much until its about -15F or so, which we do see fairly regularly. On the flip side, the 5w30 tends to be consumed much more rapidly in the summer months, so the 10w30 takes over with less consumption. As a side note, as the 5w and 0w of the world get better and better, is there any advantage to using 10w if there is no real difference in longetivity?
 
Messages
8,937
Location
SC
quote:
Originally posted by Patman: This is why I find that german 0w30 Syntec so interesting. It's got better cold weather specs than anything I've ever seen come off the shelves of Walmart, and has an incredibly good HTHS for a 30wt oil. I'll be running this oil in my sister's car through the summer, so we'll see how it handles that. I'm sure it'll pass with flying colors.
I stopped by my local AutoZone today and the do carry the Castrol Syntec 0w30. Unfortunately, it was the "Made in USA" crap. I'll keep an eye out and see if they wind up stocking the German stuff. I'm beginning to wonder now if Castrol North America is only going to import the German stuff for sale in Canada.
 

Patman

Staff member
Thread starter
Messages
21,988
Location
Oakville, Ontario
quote:
Originally posted by Quick_lude: How much is the German 0w30 Syntec at Walmart Pat? If we're talking synthetic I'd say for all but the most coldest climates you could run 10w30 all year long safely. In my case due to the characteristics of my engine I'll be using the M1 0w40 in the summer, and M1 10w30 in the winter.
Walmart sells the 0w30 for $6.66/L. I think you could run this all year long in your Prelude. If you go M1, go with 5w30 over 10w30 in winter, especially if next one is as brutal as this one.
 
Messages
5,785
Location
Dixie
Patman, You are overthinking this stuff ...it is really the quality of the oil that matters much more than if it's a 5w-30 or 10w-30. I honestly don't see much benefit in switching back and forth. A 5w-30 is going to flow more easily while the engine is warming up, but a 10w-30 may be a bit more stable in hot weather - I think it's a wash. I sell 0w-30/5w-30/10w-30/10w-40 grades of synthetic lube, but it's more due to customer demand than anything else. In all honesty I could just sell the any one of these and it would work fine. I now sell primarily 0w-30 since it offers excellent protection along with the best fuel efficiency and engine performance. TooSlick
 
Messages
352
Location
Ontario, Canada.
quote:
Originally posted by iontrap: This is a question that I'm very interested in. I've been considering switching to M1 10w30 this spring from M1 5w30. It can get brutally hot here in Georgia and I was thinking that using a 10w30 during the hot months would be a good idea.
Aren't a 5/30 and 10/30 both 30 at temperature? How can the 10/30 offer more protection? Wouldn't you have to go to a 40 weight for instance if you want extra hot weather protection? [ February 22, 2003, 10:56 AM: Message edited by: 7tford ]
 
Messages
352
Location
Ontario, Canada.
I agree with "Tooslick". This motor oil industry is getting out of hand. Those bottles all seem like so much candy on the store shelves don't they? Who tells the manufacturers anyway that Heh!!, lets start manufacturing a 0w/40. Is the Siberian landscape full of SL500's that require this stuff? My Tacoma V6 manual suggests 5W-30 at temps below 0/F and a 10w-30 above that. I assume that the R&D folks at Toyota have figured this out to be the best. Or are they deliberately misleading us so that we will wear out quicker so as to buy a new vehicle sooner. Granted the engines today are manufactured presumably with better tolerances than in the 70's and may require better oils. I've noticed though that companies are advertising longer drain intervals for their new vehicles, but not necessarily different oil at the dealerships. Or is that OEM stuff definitely better these days? I too am victim of the marketing and have experimented a little with motor oil in the past. Right or wrong I have been running the Delvac 1 5w-40 in my daily driver Toyota V6. I figured it would offer a good balance between the recommended 5/30 and 10/30 passenger car only oil, and since it isn't driven much and only has 40K in five years, I won't be dealing it anytime soon. I am using Redline 10W-40 in my Classic Mustang. This stuff is gold by the time you get it here, but I'm not using that much of it and the car is worth it. I used Mobil 5w-30 in our 93 Corolla from day one, but when I traded it in at 150K I didn't get any extra money for it. Guess these dealers don't attribute any benefit to us dedicated oil nuts using these high end oils?
 

Patman

Staff member
Thread starter
Messages
21,988
Location
Oakville, Ontario
quote:
Originally posted by TooSlick: Patman, You are overthinking this stuff ...it is really the quality of the oil that matters much more than if it's a 5w-30 or 10w-30. I honestly don't see much benefit in switching back and forth. A 5w-30 is going to flow more easily while the engine is warming up, but a 10w-30 may be a bit more stable in hot weather - I think it's a wash.
Hehe, I always overthink everythin! [Smile] But seriously, I guess I'm just trying to figure out why so many carmakers think 5w30 will flow better in the warm weather too. I agree that it flows better in cold, but once it's 70 or above outside, I really don't think the 5w30 has any faster flow to the top end of the engine than 10w30 would, and we all know 10w30 is generally a better built oil. Although the latest synthetic 5w30s are definitely better, and probably could be run in the hot summer with no wear penalty over 10w30. With the last formula of Mobil 1 I'd say no to this though, since 5w30 TriSyn seemed to thin out a lot, at least in hard driven Camaros and Firebirds.
 
Top