Thick & Thin

[dropitby]

Today there seems to be those who prefer heavy oil (15/50) and those who prefer thinner oil (0/30 5/30).I can see for your normal back & forth to work start & stop driving you may choose the 10/30 but say your going on a summer vacation and plan to drive 2000 miles. Would you stay with it or switch to the 15/50.I for one like 15/50 all the time yet I am not sure it is best all the time so which is it keep the 5/30 or run 15/50!

 

[pscholte]

dib, I am a strong proponent of owner's manual, owner's manual, owner's manual. I am glad we have people on this board who think for themselves but I think this is one case where you go with the guidance. Now as a vehicle gets older, if you start seeing increased consumption, you can go for increased viscosity but I am one who, despite all those nasty viscosity improvers, believes you start thin at the low end (e.g. 0W30, 0W40, 5W40, 5W50) if your engine ever gets to that point where you need that kind of viscosity. I have never had any issues following this regimen despite putting a lot of miles on a lot of cars in some pretty demanding conditions: sub-zero to 119 degrees and at alititudes above 10K' (I live at almost 7K). [ August 07, 2004, 01:49 PM: Message edited by: pscholte ]

 

[dropitby]

http://www.nichols.nu/tip291.htm The "Honda Engine Oil" is a semi-synthetic 15W-40 oil which is recommended for all Honda engines, including the super high spec'ed DOHC VTEC and DOHC iVTEC versions. This post didn't come out right but the words Film Strength are mentioned a lot when referring to the 15/50. [ August 07, 2004, 02:48 PM: Message edited by: dropitby ]

 

[gumby_66]

After reading many posts for and against, I decided to use a 10w40 for the summer towing my trailer with my 99 GMC Safari. Did over 8000 KMs in 5 weeks, no difference in gas mileage from previous summer. Had a great vacation and felt I was protecting my engine pulling my trailer up those long 6-8% hills in BC. Planning to go to Mobil1 15w50 or Amsoil 20w50 next summer. Steve

 

[Bill Morris]

In certain engines and driving condition you may want to consider other than that I would go what the manual states especially when the engine is new. Engines are built with tighter clearance and is the reason for lower weight engine oil and also for MPG.

 

[JohnBrowning]

Bill Morris, What are the clearances for your engine?

 

[jorton]

I am also undecided about thick vs thin. Mechanics and radio talk show hosts here say to use 20w50, 15w40 or even sae30. My common sense says an oil that can perform between ambient -36f and +100f HAS to be a superior oil. Do you think there is any 5w blend that has less burn off from additives than Motorcraft 10w30? Joe

 

[Hankrr]

Just by chance I read this article this morning concerning two engine failures. One by coolant leaked into the engine oil and the other when fuel diluted the oil. Just thinking but logicly it would seem that if one was using a thicker oil then one would have a wider margin of safty in the event of oil dilution. Personally I don't feel there is any margin for error in these types of problems with the 5W20 weight oils: Engine failures by Jim Kerr Automotive engines contain hundreds of parts that operate over wide temperature ranges and speeds. They are expected to run smoothly, be economical on fuel, produce low emissions and last for hundreds of thousands of kilometres. The technology in modern engines allows all of this to be possible, but sometimes things go wrong. Twice in the last week, I have been asked to diagnose engine noises. The two vehicles had low-pitched intermittent knocking sounds that would change when the engine speed varied. It was also louder when the engine was warm. It didn't take long to diagnose - I have heard this sound before and it was an expensive noise. Both engines had failed connecting rod bearing and damaged crankshafts. The first engine, a V8 in a 1995 Dodge Ram pickup has already been repaired. It needed new engine bearings, a rebuilt crankshaft and an overhaul gasket set. The replacement parts alone totalled several hundred dollars and ten hours labour added to the repair costs. This truck had always been pampered and has less than 90,000 kilometres on it. This is low mileage for a modern vehicle, so why did it fail? The second engine, a V6 in a 2000 Montana van still needs to be repaired, but the knock in it was even louder than the Dodge, so I expect the repairs will be even more extensive and expensive. This van has only 75,000 kilometres on it. Again, the real puzzle is why did this engine fail and how could it have been prevented? A little further diagnostic work helped find the root cause of the problem with both engines. Although the failures were similar, the causes were not similar at all. The Dodge engine failure could be traced back to an antifreeze leak while the Montana engine was done in by driving it with a misfire. We can learn from their mistakes. Several weeks earlier, the Dodge V8 had started loosing engine coolant. Usually coolant leaks are external and you find a puddle on the ground but this engine had an internal coolant leak. A failed intake manifold gasket had allowed coolant to seep into the engine and down into the oil pan. The only indication there was any problem was the coolant level in the radiator overflow tank kept getting lower. The manifold gasket was replaced, the manifold surface was machined and the engine oil was changed but the damage was already done. Enough coolant had seeped into the oil pan that some had been sucked up by the oil pump and pushed through the engine. Unfortunately, coolant and engine bearings don't mix well. The bearing surfaces smear and begin to fail. So the real cause of the bearing and crankshaft failure was a coolant leak. How could this have been prevented? Changing engine coolant at the recommended time intervals (every two or five years) found in the owner's manual will help maintain anti-corrosion protection in the cooling system. Monitoring engine coolant level regularly could have also prevented this failure because the leak could have been corrected before major damage occurred. The Montana Van's engine failure was caused by another relatively small problem. The owner was towing a large boat a couple hundred kilometres home from the lake and the van seemed short on power. He thought the problem was with the transmission. The actual fault was one misfiring sparkplug. With one sparkplug misfiring, the V6 engine only runs on five cylinders so the power is down, but when a cylinder misfires, other problems develop. The fuel injection system's oxygen sensor detects the unused oxygen from the misfiring cylinder in the exhaust gas stream. This causes the sensor to falsely signal the engine computer that the air fuel mixture is too lean, so the computer injects more fuel. Excessive fuel injected into the engine couldn't all be burned so some ran past the piston rings into the crankcase. The fuel diluted the engine oil so it couldn't provide adequate lubrication for the bearings and they failed. A sample of the engine oil showed a high percentage of gasoline, verifying our diagnosis of the cause. The moral of this story? Ignoring obvious problems can cause expensive repairs. If the owner had stopped at a repair shop, it would have been easy to diagnose a misfiring sparkplug and the problem could have been corrected for only a few dollars. Even towing the vehicle two hundred kilometres would have been cheaper than the cost of repairing this engine. Modern engines are extremely durable and reliable but they still need attention to make them last. A few minutes checking fluid levels or getting a tune-up would have prevented both these vehicle's problems. Don't let it happen to you. http://www.canadiandriver.com/articles/jk/040616.htm

 

[TallPaul]

I view 5w20 like driving along the edge of a cliff. One mistake and your over the edge. On the other hand 20w50 may be like hugging the mountain side. One mistake and you sideswipe it. The 30 and 40 weight multigrade oils are a good middle of the road path.

 

[Hankrr]

quote:

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Originally posted by TallPaul: I view 5w20 like driving along the edge of a cliff. One mistake and your over the edge. On the other hand 20w50 may be like hugging the mountain side. One mistake and you sideswipe it. The 30 and 40 weight multigrade oils are a good middle of the road path.

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That sounds like the best advise to me. Rather than one extreme or the other stay towards the middle of the road.

 

[mikemc]

In a moderate climate where temp doesn't dip below zero, for most engines I would run a good 10w30 dino all year and never lose a wink of sleep.

 

[1sttruck]

Still, one sees multi-viscosity 40W and 50W oils marketed as high performance or 'European' oils. I'd tend to take OEM recommendations with at least a bit of salt as they're also under EPA pressure to increase mileage with less concern for long term durability beyond warranty. People in the US also don't drive like they do in Europe, where I can remember being topped out on a BMW 750cc bike at about 120 to 125 mph and having cars blink their high beams at me so that I would move over.

 

[pscholte]

quote:

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Originally posted by 1sttruck: I'd tend to take OEM recommendations with at least a bit of salt as they're also under EPA pressure to increase mileage with less concern for long term durability beyond warranty.

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We see this sentiment expressed often on this board. While intuitively it is clear this could be true, and it is easy to postulate why it is likely it is true, just to keep from totally writing off outright the integrity of the entire automotive industry, I'd like to see a substantiation from someone who has worked in the business and KNOWS that this is indeed the calculus applied.

 

[427Z06]

quote:

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Originally posted by pscholte:

quote:

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Originally posted by 1sttruck: I'd tend to take OEM recommendations with at least a bit of salt as they're also under EPA pressure to increase mileage with less concern for long term durability beyond warranty.

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We see this sentiment expressed often on this board. While intuitively it is clear this could be true, and it is easy to postulate why it is likely it is true, just to keep from totally writing off outright the integrity of the entire automotive industry, I'd like to see a substantiation from someone who has worked in the business and KNOWS that this is indeed the calculus applied.

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Would you settle for some fancy trigonometry?

 

[pscholte]

quote:

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Originally posted by 427Z06: Would you settle for some fancy trigonometry?

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427.. Nice...VERY VERY nice!

 

[jorton]

In the 2 failure examples, Hankrr didn't mention thick or thin. A motor lasts hundreds of thousands of miles with 5w-30 or 20w-50 unless some other $3 part fails. Our problem is choices. When we go to the store to buy oil we would like to choose the best quality and value and use the same choice every oil change. I use the info at BIOG to help make this choice and when I get to the store all the colors and names and prices are overwhelming! But it's ok if I get the red, white, yellow or blue bottle, or something thats on sale because that doesn't have any bearing on when some $3 part is going to fail. Joe

 

[Ugly3]

Two thoughts on the topic. First - it is generally understood that a great portion of lifetime engine wear occurs at cold startup. That would suggest a thinner oil (within the recommendations of the car maker) would provide the greatest benefit. Second - after looking at the Pennzoil 250,000 mile warranty program I find no reference to viscosity. The Shell commercial truck warranty requires the makers viscosity recommendations to be followed.

 

[Tim]

For those who swear by the owner's manual, I think it is interesting to note how CAFE rules affect what the manufacturers recommend. Example - Toyota recommends (for the Land Cruiser) 5W-30 at temps in the U.S. that call for 15W-40 in non-U.S. locations with no CAFE issues. So, eliminate CAFE in the U.S. and guess which viscosity they would recommend.... The owner's manual is not necessarily the best place to find good oil recommendations. Sometimes it pays to be skeptical. Tim

 

[williar]

When I run 40w oil in engines designed for a 30w the oil pressure runs too high, even in the summer under load. So, it's back to a good xw30 wt for me! Seems the engineers know what they're doing on viscosity recommendations.

 

[moribundman]

When choosing an oil, I will lean towards the heavier recommended oils for that particular motor. I feel a heavier oil suits my engine and driving style better, with an added safety margin.