5w40 too heavy?

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Last oil change on my 3.4 V-6 GM engine, I put in Havoline 5w40 Synthetic (Big Lot Special). 5w30 is recommended, but for the summer, I thought I'd give this a try. Well, while mileage didn't suffer at all (did just as well), the engine seemed bogged down or less peppy. Changed the oil yesterday and put in 5w30 Valvoline Synthetic and the engine seemed to have a little more life to it. It wasn't just me, the wife had complained about this too. I'll see if she notices any difference now that I've changed oil. Any thoughts? Thanks.
 
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Yep, you will definitely notice a difference. All you accomplish is to kill off some Hp and add to heat buildup a bit. You might notice the engine warms up faster in cold (below 32F) weather. I'm may get flamed, but the GM V-6's just don't need a 5-40 or 15-40. It will work, but....
 
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quote:
Originally posted by haley10: Yep, you will definitely notice a difference. All you accomplish is to kill off some Hp and add to heat buildup a bit. You might notice the engine warms up faster in cold (below 32F) weather. I'm may get flamed, but the GM V-6's just don't need a 5-40 or 15-40. It will work, but....
And then there's people like me, driving little 4-cylinders, that are running 40-weight oils instead of the designated 30-weights with no noticeable effect on fuel economy or performance. Just goes to show the same rule doesn't apply to every single application.
 
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Yep, kev99si, this is for sure true. All 40wt.s aren't created equal, either. A lite 40wt. that is friction modified might work well. That's why we experiment to see what works for us. I'm running a lite 10W-40 syn in my GM 3.8L and it's fine, generally not the best idea, though , 12 cst is plenty enough for these.
 
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I;m in FL where it's 95-100F daily, I run a 10W-40 (just switched( and will be doing analysis comparing it to the previous two 10W-30 runs. [Smile] I think it runs better actually.
 
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quote:
Originally posted by kev99sl:
And then there's people like me, driving little 4-cylinders, that are running 40-weight oils instead of the designated 30-weights with no noticeable effect on fuel economy or performance. Just goes to show the same rule doesn't apply to every single application. [/QB][/QUOTE] Interesting, I have a bought new, a 1996 Ford Contour 4 cylinder 2.0L Zetec engine and when it was about 2 years old I started running Syntec and Quaker State 5W-50. Because I thought "thickerer was bettterer". NOPE, not in my case. I lost several mpg and lost significant "seat of the pants" feel. Previously I was using Mobil 1 5W-30. I went back to 5W-30, Mobil 1 and Exxon's synthetic and I regained my old mpg and pep. I'm now using Schaeffers 5W-30 Blend and same pep and mpg as Mobil 1. The ironic part is this engine is European designed where thicker oil is the norm. Go figure [I dont know] . Whimsey
 
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And, as I've posted on here before: I changed one car from 10W-30 to a 15W-40 and am consistently getting better performance and increased mpg. What works for some apparently does differently for others.
 
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Originally posted by krholm: And, as I've posted on here before: I changed one car from 10W-30 to a 15W-40 and am consistently getting better performance and increased mpg. What works for some apparently does differently for others.
Just curious, what kind of car and engine are you talking about. Is it a "loose" older pushrod or a new OHC engine, American/German/Japanese or what? Because in all honesty it seems rare to get BETTER mpg and horsepower/"seat of the pants feel" unless the engine was worn or originally built for heavier oils. "Enquiring minds want to know" [Big Grin] . Whimsey
 
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My experience with a Taurus w/ 3.0 Duratech... I always used motorcraft 5w-20. Then I switched to Chevron supreme 10w-30; no difference. Now I decided to try something thicker; 1.5qts of Pennzoil 15w-40LL, 2.5qts of Shell Rotella syn 5w-40 and 2 qts of Chevron supreme 10w-30. To my surprise; low-end feels the same, but the mid-range and top-end feel stronger! Now I need to check MPG.
 
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mini-rant: How come everybody posts oil analyses and argues about parts per million but also makes all these qualitative statements about performance and we never see any 0-60, 1/4 mile, or G-Tech data?
 
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I get same/better performance with 15w-40 vs 10w-30 in my '93 Range Rover. The engine is nearly unchanged since it was originally introduced in '63. The bearing clearances are very large (.010 -.048mm) - a loose engine - versus others. The rattle visible and audibly around when you first install them. It relies on large volume, but low pressure (max about 45 psi even cold). I found a lot of bearing shell wear when I took apart the bottom end. The previous owner had used a lot of 10w-30. I think the thinner oil washes out of the bearings too easily in these engines and reduces oil pressure elsewhere. [ July 15, 2004, 10:33 PM: Message edited by: Geoff ]
 
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quote:
How come everybody posts oil analyses and argues about parts per million but also makes all these qualitative statements about performance and we never see any 0-60, 1/4 mile, or G-Tech data?
Not every aspect of oil evaluation has to be analytical! There is a VOA and UOA section for that though. [Big Grin] These are just our subjective observations; nothing more; nothing less. [Smile] I'm not really inclined to take the Taurus to the strip but I'll gladly put your G-Tech to good use! [Big Grin]
 
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i have two slant six cars that love 5w-40, with any 10-30 oil they sounded like they had marbles shooting around in the oil pan. thicker oil, less noise and less oil use, just towed a full uhaul trailer with one 1000miles and used just enough on the dipstick that i could tell it moved. but both cars are over 25 years old. Dan
 
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I gotta take back my post above. I am finding plenty of examples (Mitsbishi, Dodge 2.4l, Ford Modular, etc) with larger bearing clearances. Go figure.
 
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quote:
The engine is nearly unchanged since it was originally introduced in '63.
[Off Topic!] Yeah, I believe that engine was designed and used by Buick, then they sold the tooling to Land Rover.
 
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Then there's my experience...first OCI with Havoline Synth 5-40 (SJ) after using BMW 5-30 synth and the car ran like a scalded goat! I think the Havoline synth. is a great product....
 
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quote:
Originally posted by Dr. T: Then there's my experience...first OCI with Havoline Synth 5-40 (SJ) after using BMW 5-30 synth and the car ran like a scalded goat! I think the Havoline synth. is a great product....
I didn't know that scalded goats were very fast...
 
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Greased pigs are slippery and oiled lightning is really fast. [Off Topic!] Oh yeah, and 5W-40 is really thick. Ever wonder how an old Beetle with 35 hp ever got off the spot with 20W-50 in the crankcase? [Razz]
 
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quote:
Originally posted by Whimsey:
quote:
Originally posted by krholm: And, as I've posted on here before: I changed one car from 10W-30 to a 15W-40 and am consistently getting better performance and increased mpg. What works for some apparently does differently for others.
Just curious, what kind of car and engine are you talking about. Is it a "loose" older pushrod or a new OHC engine, American/German/Japanese or what? Because in all honesty it seems rare to get BETTER mpg and horsepower/"seat of the pants feel" unless the engine was worn or originally built for heavier oils. "Enquiring minds want to know" [Big Grin] . Whimsey

---------------- Wow Whimsey, sorry for the upset. I really didn't mean for my post to have that effect. However, I learned some time ago that some will attack when they don't like results that get posted onto this forum. But, please again, don't take this personally. The car is a 99 Nissan Sentra 1.6L engine w/auto transm VIN 3N1AB41D8XL07986 w/ 80k miles on it. I've always kept exact records of fuel usage on highway trips with it. It had long been on a diet of 10W-30 Scheaffers Blend. I had always gotten 31 mpg on road trips. In early April I changed this car to Schaeffers 15W-40 Blend and started my trip. Careful record keeping reveals an increase to 34.95 mpg. on a 6,020 mile journey. The fact that better performance is subjective is understandable but I've driven this car a lot and I know what it feels like. It's too bad that you've let this bother you but it just happens to be the fact.
 
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