5W20 in a pre 1990 engine

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Our daughter is now driving our 1988, yes, 1988 Honda Accord with over 300,000miles on the clock. This car has been very well maintained by me and the OCI has been 3-4000 miles using the dino recomended 5W30 -10W30 motor oil. Purchaced new, this car has been driven up and down the east coast over the past 17 yrs between NY & FLA. Our daughter is complaining about her out of pocket $$$ at the fuel pump. The engine is in good tune and I have performed good MPG practices on the car over the years. The fuel economy is still the same when new, beleive it or not and the engine does not burn or leak any oil. I'am currently using 5W20 motor oil for the most recent oil/filter change only to see if the MPG will increase. My daughter driving habits consist of to and from high school and work. Both trips consist of aprox.5 miles each way. She also does a little running around with friends to malls and school activities. All trips are very short distances with long engine shut downs between restarts. Should I be concerned with the 5W20 motor oil or should we just stick with what has worked over the years....Responces Please!
 
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I sure ain't no authority, but, danged if I would switch after 300k and not burning or leaking oil
 

Char Baby

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This has been the most ammazing car that I have ever owned from a reliability and repair factor. I always put several hundred thousand miles on an automobile, but none with as few repaires as this one.
 
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Stick with a 30 wt oil . I tried 5w20 in my wife's 1998 Civic (which calls for a 5w30) and gas mileage dropped about 5 miles per gallon. Don't waste your time with a 5w20 on such an old car.
 
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Just my opinion, but I'd rather rely on my motor oil for lubrication, and look to other methods for saving $ on gas. Here's a good link by Chevron for Gas Mileage Factors. See figure 3, about 2/3 the way down the page. Simple things, such as tire pressure, a light foot on the gas pedal & emptying extra weight out of the trunk, will achieve the same 1-3% mpg gains as switching to 5W-20 oil.
 
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My stepfather has a 1990 Accord with 299000 miles, he's running 4 quarts Valvoline Maxlife 10w30 with one quart Maxlife 5w30. I would go with a 10w30 in the warmer months, then switch to 5w30 for the colder months. No need to mess with what's been working for that motor for the past 17 years. I doubt using a 5w20 would net any very noticeable fuel economy benefits.
 
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I try to follow the old saying "Don't fix what is not broken". I would just keep using what got you this far.
 
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You are probably better off with the 30wt. The short trips could result in fuel dilusion and higher wear. Just to be safe, it might be helpful if you have a UOA done.
 
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With such short trips I doubt that there is much of a difference. The 5w20 probably is a little thinner in this driving cycle but it is not as thin as the 5w30 would be if it was driven to full operating temperature. So basicly your oil is still to thick [Wink] Then again your daughter could be a hot foot. [Eek!]
 
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I ran M1 5w-20 in the late 70's, early 80's and didn't see problems . The newer 20w oils have more add pack than that did. For a definitive answer get an oil analysis and we can tell you without guessing. www.dysonanalysis.com
 
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Hi, this may be of interest; "For 1941 Model US Cars Oil grades for all Makes and Models The most common recommendations for in-line 4, 6, 8cyl and V8, V12 follow; Engine: Over 32F = 20 or 20W (highest 30),then some 90F> 30,40(highest 50) Over 10F = 20W (lowest 10W) Over -10F = 10W Below -10F = 10W (plus 10% Kerosine - for all vehicles except Crosley)" DH Note; most of us will not need to worry about remembering NOT to use Kero in the Crosley! The 5w-20 would have been great back then and no Kero at all in the others either!!! Regards Doug
 

Char Baby

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Benjamming, The oil was Valvoline SL/GF-3,(4 qts) that a friend had given me. He used it in his 02 Civic that he just traded in for an 05 Camry. Thanks to all respondants. I'll go back to the normal 5W30 for winter, 10W30 in the summer after this oil change is complete,(maybe I'll dump it early)! I just wanted to see if there were any MPG benefits with just the oil alone. Like I stated in my first post, the engine is in good tune, and as Blue99 has sugested, I do follow good MPG practices.
 

Char Baby

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My sister-in-law just purchaced a used '03 Prius(hybrid) for about $13,000. This really is not the road that we want to take at this time...I just wanted to see if our daughter could get a little better MPG with 5W20 motor oil that a friend had given us,(4 QTS). As I metioned before, the engine is in good tune, and all fluids(ATF, OCI, coolant flushes, wheel bearings lubed), have been done on an regular basis. Proper wheel allignment with very good tires properly inflated,(often 1-3 lbs. psi over spec). On the last 3 tankfulls of gas, the MPG has been...24.7 mpg, 25.1 mpg and 25.5 mpg. All run-a-bout type driving,(city only!). This is about the norm for this car, often in the past reaching 27 + mpg city, in the summer months only. Winter months is about 18 - 21 mpg in the city. The EPA for this car equiped with and auto trans like out car is 24 city - 30 hywy, according to the original brochure that we still have. We have always gotten 24-27 in the city and 34-38 on the hywy.(climate dependant), over the past 17 years. Thus far I don't see any MPG benefits of the 5W20 motor oil, so I may dump it early. Over the past 5 years or so, I have replaced the gas tank, radiator/thermostat and all hoses, air conditioning condenser, alternator, rusty brake lines/high pressurs lines, power steering lines etc., hoses, belts, vacuum lines, water pumps with the timing belt changes, fuel pump & relay, coil and igniter, and of course brakes and exaust parts. Just recently installed a brand new carburator choke t-stat, and a cheap Wal-Mart in dash CD player. Starter is still OE as are many other parts. We'll probably continue driving the car until it doesn't pass state inspection any more and then give it away as we have done in the past. Paid $13,000 cash for this car in '88. The best money that I have ever spent on a car. My brother-in-law workes on International Harvester, Allice/Chalmers, Hatachi, Kumatsu and other deisel rigs and heavy equipement. He has helped me perform some of the duties listed above. He can't beleive how well this car is constructed. He drives Buicks as a rule and never has problems with them,(good MPG too!).
 

Char Baby

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This last tankfull of gas is 26.77 MPG. Seem to be consistantly climbing. Weather is getting better also. Outside temp was in the high 80's low 90's . Still can't tell if there is any fuel economy benefits of using 5W20 oil, it's only been a month! This is only a test. I may even have Terry do a UOA just for the data on a 328,000 engine.
 
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My '72 Plymouth 318 gets 17-18 winter and 19-20 summer. I could plot the mpg vs. months for last 5 years and would be a sine-wave appearing curve. Maybe due to lower density molecules for winter fuels? [ June 19, 2005, 10:18 PM: Message edited by: HerkyJim ]
 

Char Baby

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Herky Jim, My dad had a friend many years ago with a 59 CADY. He was getting 19mpg all day long. I myself had a 69 Biscayne that did quite well. Love that old American Iron! My actual goal is to see wheather or not this engine can achieve close to 30mpg on the city cycle with 5W20 motor oil. This type of mpg has never happened before with this particular car. Best we have achieved IIRC, is close to 29mpg on several occasions in the summer months on the city cycle. The weather during these particular summers was just supurb! It looks as though we are headed for a very nice summer this year here in Upstate NY. If this old Honda dies tommorow, it won't owe us a dime!
 
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Around here in western canada, I'm sure we get worse fuel economy in the winter because of increased oil viscosity in transmissions, transfer cases, differentials, etc. when temps are below freezing. You can just feel how much extra horsepower is required, and how much further you have to push down on the gas pedal to move the car, you can even feel the shocks get really hard when it's super cold out. That and the engine running richer in cold temps probably account for alot of the decrease in MPG.
 
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