5w-30

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  #1  
Old 04-25-03, 02:27 PM
Huxley
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5w-30 Oil

Will it hurt to run 5w-30 in the summer time in a 1991 car? The summer highs here get to about 100. The car runs better on this weight of oil.
 
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  #2  
Old 04-25-03, 02:49 PM
darrell McCoy
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Owners manual or on top of oil filler cap should tell you what this vehicle should use. I live east across the river from you and I use 5/30 in both p/u and car year round. Lots of dealers use 10/30 around here unless you specify otherwise. The 30 part should be fine for summer/winter. The 5 part is better in really cold weather.
 
  #3  
Old 04-26-03, 06:16 AM
Joe_F
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I agree with Darrell. Follow the owner's manual.
 
  #4  
Old 04-26-03, 08:20 AM
Join Date: Dec 2002
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The viscosity of an oil is it's resistance to flow. There are many properties of oil that you need to consider. 5w30 will have less resistance and help provide slightly better fuel economy and less windage, and with the strict C.A.F.E. standards auto manufacturers are trying to squeeze every last drop of MPG out of their cars in production. Here are some factors you need to consider that are properties of engine oil.
It:
Lubricates
Cleans
Cushions
and Seals the engine.

The cushioning effect that oil has is its most important factor you should consider. The thicker the oil the better the cushion. So in extreme heat 5w30 will not provide as much of a cushioning effect between the bearings and connecting rods to the crankshaft where you have a piston that can be traveling at 1500 feet per second. So 5w30 may help fuel economy slightly, but may also punish your engine a little more. I would personally recommend in the summer running at least 10w30 depending on how tired your engine is.
 
  #5  
Old 04-26-03, 03:00 PM
Gomer-techimo
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Yamaha:
Does not the 30 in both 5w30, and 10w30 indicate that they both behave the same in high temps?
 
  #6  
Old 04-26-03, 08:27 PM
Joe_F
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Yamaha:

I disagree. The first weight in an oil # is for the winter. Going into the summer 10 and 5W30 provide the same protection .

However, 10W40, while the same as 10W30 for winter is made in such a way that I believe 10W30 is a more "stable" type oil due to the blending of oils to make the 10W40 multiblend. Dan Meyer of this forum would be better suited to answer that.

Always stick with the OEM recommended grades. If the engine looses the OEM grade oil, there are leaks or the engine is wasted and needs a rebuild. No need to use molasses when peanut oil would do .
 
  #7  
Old 04-26-03, 09:16 PM
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Gomer, Yes they will both behave like a 30 weight when hot 212F but not when cold. (like at start up) You are talking about multi-viscosity oils that use polymers that expand when heated. In 100 weather summers I would use the 10w30. And Joe, if you disagree that is fine but This guy is talking about his 1991 clunker that would be better suited for a slightly heavier oil as opposed to replacing the engine or doing an overhaul because it's starting to show its age. I speak from experience and unless the ambient temp is below 60F I think 10w30 is a better pick for your car.
 
  #8  
Old 04-27-03, 11:05 AM
Dan Meyer
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JoeF is correct.
The first number is the viscosity of the oil at "cold" temperature. The second number is the viscosity at 100 F. So any multi vis oil with the second number the same (5W-30, 10W-30, 20W-30 all have the same ,or nearly so, the SAME viscosity at 100 F.

A 10W-30 multi-vis oil starts out as a 20 weight to which polymethacrylate is added to give it the multi temp properties.
As the oil is used, the poly additive is "sheared" out and the oil loses its multi temp properties.

It is correct that a 40 weight will give more "cushion" at higher temps and somewhat "seal" worn parts. And yes, a 30 weight will give better gas mileage. But I doubt that the amount of gas saved could even be measured.

My personal opinion: I wouldn't consider the fuel economy. I would go with the heavier grade oil for wear protection (except in the winter for cold starting).
 
  #9  
Old 04-27-03, 01:57 PM
Joe_F
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Yamaha: I was referring to the fact that 10W30 and 5W30 behave the same in the summer, one is not "better" than the other.

Original poster: Does the vehicle use any oil? If not, the OEM grade is fine. I run all OEM recommended grades in my machines, all are spotless inside and do not burn any oil.
 
  #10  
Old 04-27-03, 08:31 PM
Huxley
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5w-30

It does burn oil get about 500 miles to the quart. I don't make much money so I have to keep driving it. The good part of the story is that I drive about 500 miles a month that cost me about .88 cents a month not a bad deal.
 
  #11  
Old 04-28-03, 05:46 AM
Joe_F
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Yes, the vehicle is on borrowed time. Thicker oil will help for a while, but you're going to have to replace the vehicle or rebuild the engine eventually, whatever type of vehicle it is (You don't say).
 
  #12  
Old 04-28-03, 06:43 AM
Huxley
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Car

It is a 1991 Dodge Monaco with 142,000 miles on it not many of them around nowdays.
 
  #13  
Old 04-28-03, 07:40 AM
Joe_F
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Yes, they were of very poor quality and were being phased out in favor of the LH body sedans (not much better)
 
  #14  
Old 04-28-03, 05:45 PM
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Location: corona Ca.
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Yamaha-not to add fuel to the fire, but I take personal offense at the statement "his 1991 clunker"; when you posted that statement, you had absolutely no idea what type of car it was--for all you know it could have been a vette, a diablo, or mustang.

Attitudes towards older vehicles need to be checked---as many peoples livelihoods and passion go into "older" vehicles.

I would say that someone who owns a 2003 hyundai or a kia etc is guilty of driving "junk" more that someone who owns a vette, a camaro, a mustang, an American full size truck, or even a turbo eclipse from the 1991 vintage, I would take any of those cars over half of today's new cars.

I am sure you meant no harm, but I wanted to point out that some people who can afford to own a new car drive older cars by choice. (yes I have 2 cars less than 5 years old, and 4 cars 17 years and older.
 
  #15  
Old 04-29-03, 06:26 AM
Joe_F
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Good point Jeremy. The vehicle in question is no stellar vehicle; however, not everyone drives and owns a vehicle for the love of doing so as you or I do.
 
  #16  
Old 04-29-03, 07:17 AM
tstokka
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so why does my car start using oil after 3000 miles?
 
  #17  
Old 04-29-03, 07:55 AM
Joe_F
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What type of vehicle? What's the maintenance history?
 
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