Which oil for -30 starts

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Aug 31, 2003
Moorhead, MN
I live in northern MN (-30 is not uncommon). I drive high mileage 307-V8s in my old Cadillac rear wheel drives. I plug-in when it gets below zero for engine starting protection(but I travel and may not have a plug), I have always used Pennzoil 5W30 dino. Most of my cars have over 100,000 miles and are garaged. The old Pennz has worked fine, but i want to go for Maxx miles on my cars. Please recomend the type of oil to use in winter months; Synthetic, the new high mileage, or stay with regular Pennz? [ September 28, 2003, 02:00 AM: Message edited by: Ironthinker ]
I used Mobil1 5w30 in the winter, have for the last 11 years. This year I will try Chevron syn 5w30. Mobil1 worked great, never had a start up problem. At -30F my old Dodge Ramcharger would fire up without being plugged in.
Under conditions like that you definitely want to be using a 5w30 synthetic or even a 0w30 synthetic. I would lean towards Amsoil 0w30 or German Castrol 0w30.
Synthetic would be best. Also, you might want to consider an oilpan heater if you're only using a coolant/block type heater. I've seen heated dipsticks, and heated magnets for the pan. I've used the Mobil1 5w/10w and 0w-30's. The 5w or 0w synthetics are your best bet. I also understand that Pennzoil/Quakerstate have a new winter blend out. Since you've always used Pennzoil oil, you might give it a try.
Ironthinker, I live in the Walker area in Minnesota, just south of Leech Lake. I used to use Amsoil then switched to Mobil 1 5W30 (have used 0W30 also) around 1998. Never have had any problems starting but I do keep my car garaged (not heated though). I am now using Pennzoil 5W30, and will stay with it this winter. The newest SL ratings on oil have really brought up the quality of the regular oils to where I am now of the opinion that they will do a very good job of protecting and lubing within the 3,000 to 5,000 mile range (depending on one's conditions). If you keep your car garaged and use the 5W30 (maybe even 10W30) Pennzoil (it has a very good low pour point, -44 for the 5W, -33 for the 10W), I don't think you will have any troubles starting. Now if you are going to leave it outside, well then, up here, I would still feel safer with the 5w30 Mobil 1. Good day, Steven
Ironthinker, If you want something less expensive, I'd suggest the Petro Canada, "Duron" 5w-40 synthetic, which is formulated for gas/diesel engines. This oil is nice and thick at high temps, so it should be good for an older Caddie. It's a high quality, group III oil that goes for about $15.00/gallon. I've tested this oil in my own vehicles - it works very well. TS
If you afford synthetic for the winter that would offer a huge improvement. Any of the 0-30,0-40, or 5W30 synthetics from Mobil,Amsoil,Royal Purple or Redline would be a huge step up. I knew alot of guys that ran regular oil dureing the warm months and just ran synthetic for the winter months.
Based on what I have learned here on this site my solution would be to run Auto-RX for the last 1000 mile of your current Pennzoil 5w-30, then fill with Mobil 1 0w-30 for the winter.
I have to second the Petro-Can Duron recommendation. I currently use the Duron XL 0w30 in my GMC Sierra and it provides good oil pressure in the summer, better than OTC PCMO 5w30 and fast oil pressure on cold starts.
The PC, 0w-30 has a viscosity of approx 12 cst @ 100C and a HT/HS of approx 3.6 Cp. So it qualifies as an ACEA A3/B3 oil in that regard. It is significantly heavier than most of the OTC 5w-30 or 10w-30 oils you are going to find. The PC 5w-40 is 15.4 Cst @ 100C with a HT/HS of 4.2 Cp - similar specs to Delvac 1. TS
Ted, wouldn't you think a 0w30 or 0w20 would be a better oil for extreme cold compared to a 5w40 or 0w40? My view is that many of these 5w40s and 0w40s have very thick 40C viscosities, and tend to show not as good cold cranking numbers, so they might be better suited for slightly warmer weather than a 0w30 or 0w20 would be. Plus how many cars truly need a 40wt oil in very cold winter, especially since you wouldn't see your oil temps go nearly as high as they would in the summer. For someone who doesn't drive very hard in the winter, and especially someone who does short trips, now that I think about it a bit more, I think a 0w20 might work out best. It might just retain it's original cold cranking numbers a bit better than a 0w30 oil would. This is one thing we never see in UOAs, and that is how an oil degrades on it's low end. I get a glimpse of it with my lab doing the 40C viscosity as I can see in some cases the oil will thicken at this viscosity even when the 100C value doesn't shift. So if it's thickening at 40C, this tells me it's cold cranking numbers might not be as good. It could mean that someone who puts in 5w40 at the beginning of the winter might end up with an oil that is technically a 10w40 by the end of the winter.
Patman, Yes, a 0w-30 will flow easier than a 5w-40 or even a 0w-40 during the warmup phase. I'd run the Amsoil 0w-30 under these conditions. If you compare a 0w-30 to a 5w-40 @ 40C, the 5w-40 is already much thicker. TS
I don't even think these oils exist, but for my Firebird I believe it would be nice to have a 0w30 for winter and a 5w40 for summer, but both of those oils would need to come from the same company and use the same basic additive package, otherwise I wouldn't feel comfortable switching between the two. But no oil company that I'm aware of makes a 0w30 and a 5w40 which are virtual clones of each other. I know Castrol Belgium makes a 5w40 but I am pretty sure it's nowhere near the same as the 0w30 German Castrol I'm using now. Not many people switch viscosities from winter to summer anymore but it's probably the best way to get an oil that is more fine tuned, one that's better in extreme cold, the other better in extreme heat. In the future I really do see myself using Amsoil ASL 5w30 in the winter, and then their 10w40 in the summer and this would offer me excellent protection for my LT1 Firebird. I'm pretty sure these two viscosities of Amsoil are very similar in their base oil/additive pack aren't they? So switching from one to the other shouldn't pose a problem if I continued a constant 6k oil change interval? Their 0w30 would definitely be good for winter, but is probably not quite the same setup as the 10w40, so switching between those two might not be as good an idea. [ September 28, 2003, 03:28 PM: Message edited by: Patman ]
Patman, The Petro Canada Duron 0w-30 and 5w-40 use a very similar additive package, but they are Group III's. In fairness they are very reasonably priced if you are sticking with 10,000-12,000 km drain intervals. The Amsoil 5w-30 and 10w-40 do not use the same add pack. The 5w-30 is SL/CF and the 10w-40 is SL/CI-4. The 10w-40 uses primarily calcium with a little Mg, the 5w-30 uses about 2400 ppm Ca and 800 ppm of Mg. The ZDDP levels are pretty close in both formulations. The 5w-30 is also friction modified, but the 10w-40 is not, since it's also intended for use in wet clutch motorcycle engines. Up in Canada where the summer is about 2 weeks long, I'd just use the 5w-30 year round.
Patman, I'm surprised you don't want to try Delvac 1 in the summer months for your LT1. Or a mix of of M1. It's readily available. [I dont know] For the coldest of winters, in Canada or Minnesota, I'd run Mobil 1 0w-20 or German Castrol 0w-30. [ September 28, 2003, 03:48 PM: Message edited by: buster ]
With regards the PC Duron 0W-30, are you referring to the "Duron XL Synthetic BLEND 0W-30?? Reason I ask, is becauae I can't find any information on the 0W-30 GRIII "full" synthetic. Thanks, Paul
Duron XL is a blend, yes. It carries all the various ratings so it should be a good product, even though it is a blend. I have wondered myself why the 0w30 is a blend and the 5w40 is full blown.
Ironthinker, for the money and overall value I recommend Amsoil (ASL) 5w-30. Best cold weather oil bar none. Their ATM 10w-30 isn't too bad either. Unless the fine Amsoil dealers that are site supporters here know of some new formulation changes my recommendation remains. I don't have any customers running the other oils mentioned in that cold of a cranking situation. Alot of the group II and other synthetics do well on cold crank but leave you to pump molasses. Those 2 Amsoil recomendations are time tested and patterned after the mil spec arctic oils. FYI Amsoil ATM cranks at 2000 cP ASTM 5293 pumps at 6200 cP,ASTM 4684. for comparison Schaeffers 10w-30 blend cranks at about 3100 cP and pumps at 29514 cP. The old trisyn was 2500 cP crank, 8600 pump for comparison. I don't have data new enough on the Super syn formula. Big diff if you NEED a real cold soaked start and exceptional pumpability.
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