Does this make sense?

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May 3, 2003
Melb, Aus
The Nissan manual for the S15 2.oLtr recommends 10w-30 for temps above -4F. However on the chart it shows 5w-30 from -22F to +59F and 10w-30/10w-40/10w-50 from -4F to 104F+. It also says 5w-30 should only be used in extremly cold conditions on turbo models, which matches chart. Forgive me if I'm wrong here, but at operating temperature isn't a 5w-30 and a 10w-30 the same? As no mention of synthetics is made I would gather these relate to dino oils. BTW: Where I live it only gets down to about +14F (0C) a couple of times a year in the morning. What are board members thoughts on this? If the 5w is a concern, why does the dealer use a dino blend 7.5w-30 and M1 5w-50?
It's true, at operating temp, a 5w30 and 10w30 of the same brand are virtually the same, at least when new, but with a 5w30 conventional, it will thin out fast, so after 1000 miles there will be a big difference between the two. If you take a pair of good quality synthetic (not group 3) 5w30s and 10w30s though, they should be identical at operating temp even after many thousands of miles, since the 5w30 won't thin out.
Patman nailed it. This is an area where synthetic shine. There is no reason a good syn. 5W-30 shouldn't be pretty equal to a 10W-30. Sometimes oil viscosity recommendations in car manuals can be an interesting read. I guess they need to sight in on the lowest common denominator. The best thing to keep in mind from my point of view is that "wider spread" dino oil will be the weakest at actually holding viscosity at either end. Synthetic will do better, but even a 5W-50 synthetic is a super stretch. Maybe I'm reading your post wrong but I was thinking 0°C = 32°F? If this is the coldest, stay with a 10W and again a synthetic 15W would even be OK.
Guru, The recomendations of engine manufacturers are normally based on the use of average quality petroleum oils. This is particularly true in the case of domestic engines, where API, SL rated oils can vary widely in quality. I have found over the last 18 years that you can often substitute a high quality, low viscosity synthetic lube and improve performance, while maintaining or improving engine protection. As a general guide, you can use a 0w-30/5w-30 synthetic in place of a 10w-30 petroleum oil, even in hot climates. Tooslick
How old is the vehicle? older oils did exactly as Patman said and the vehicle manufacturers knew that, so recommended grades as they did. One of the big pushes over the years has been to get the light multigrades (conventional and synthetic) to be durable. With enough durability a 5w30 could be recommended for year round service and save millions of gallons of fuel year nationwide.
The car is just going on 12 months old, however they have cease production after 8-10 years using basically same engine design. SR20DET. As the manual doesn't refer to synthetics then I think Patmans answer seems to make sense. The dealer puts in either a dino 7.5-30 or M1 5w-50, which I think is a bit to heavy for a 2 litre turbo. Its the only grades of oil they have in their shop, go figure!
I have the SR20DE in my 2001 Sentra. The engine is bullet proof-big time. The only supposed knock is that is oil passages are a tad on the small side and it needs to be reved occasionally to keep them clear of sediment/varnish etc [Roll Eyes] Anyway that engine will be perfectly fine no matter what you put in it. 10W-30 Mobil 1 would be a fine choice even down to -10F and occasionally lower. I have used 10W-30 Mobil 1, 5W-30 Schaeffer's pure syn and 10W-30 Schaeffer's blend. I am not the least bit fearful of going with the Delvac 1 5W-40. Do you have the Turbo??? The engine has been known to do 400+ whp. [ October 19, 2003, 07:47 PM: Message edited by: Al ]
Hi, Mine is the turbo version, don't think the dealers every sold the non-turbo version. I think the official immports were the S14 & S15, which has stop production over 12 months ago in Japan. I think April. However there was/is a big market in importing S13's and 180sx's as they cold be imported, due to Nissan not selling them. The S13's are getiing to be 10 years old which really means that it is difficult to get a good one. Most imports were "drift" cars. Standard power here is 145kw, as they are detuned due to the fuel quality. I believe the NZ cars are 185kw, but these don't run catalytic converters. (could be wrong on the cats). I think this works out for mine as abt 105-110kw at the rear wheels. My sons 180sx with the SR20det runs 165kw+ at the rear wheels. It goes!
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