Not so Good Engine Behavior With Mobil1 5W40

For the past few months I've been using Mobil1 0W-40 with good results - good power, good gas mileage, and easy cold starts. For whatever reason, this oil change I decided to try that new Mobil1 SUV & Truck 5W-40 oil. My car has a gas powered engine but it calls for 5W-40 viscosity. I changed the oil and drove the car after that. The morning after the oil change I had to crank the engine for 4 seconds before it finally started. Now the cranking went down to 2-3 seconds. When engine is cold it's very rough. Gas mileage went down to the point where I can actually notice the difference without writing down any numbers. The engine is much more quiet now but it takes some 20% more open throttle to get the same acceleration [Confused] With 0W-40 the engine took relatively long time to warm up. With this 5W-40 engine warms up some 40% faster - I guess the heat transfer/flow rate of this oil is not so high. Bottom line, I'm going to dump this oil as soon as it starts to get dark and I will go back to 0W-40 [Frown]
 
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2,149
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USA
I bought Mobil T/S 5-40 but it was for V-8 cargo van with a heavy load. I was deciding with the Amsoil 15-40 diesel or the Mobil 5-40 and was told they both would perform well. Since it's readily available and on sale I bought 2 cases. I think your engine is better off with the Mobil 0-40 unlike the 5-40 is for heavy driving and need the shear stable in heavy application.
 
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15
Location
Illinois
quote:
Originally posted by TheNauseator: I changed the oil and drove the car after that. The morning after the oil change I had to crank the engine for 4 seconds before it finally started. Now the cranking went down to 2-3 seconds. When engine is cold it's very rough. Gas mileage went down to the point where I can actually notice the difference without writing down any numbers. The engine is much more quiet now but it takes some 20% more open throttle to get the same acceleration [Confused] With 0W-40 the engine took relatively long time to warm up. With this 5W-40 engine warms up some 40% faster - I guess the heat transfer/flow rate of this oil is not so high. Bottom line, I'm going to dump this oil as soon as it starts to get dark and I will go back to 0W-40 [Frown]
These observations are vague. 1 second extra cranking time? So what! Have you taken into account the fact that winter is over? Of course your car warms up faster. It has nothing to do with the oil. Your 20% more throttle means you've got an engine problem. Mobil-1 is not to blame. Something else is going on.
 
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1,130
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California
I highly doubt that whatever you are noticing is a consequence of changing between those two oils. Maybe your gas stations switched from a winter blend fuel to a summer blend. Maybe something else went wrong like one of the engine sensors has gotten marginal. Maybe you bumped a hose or wire loose when doing the oil change. Unless you actually took measurements of cranking time with a timer whilst using controlled starting procedures then it is also possible that you only think something is different. Whatever the story is, I would bet a case of beer that the difference between M1 0W-40 and 5W-40 is not causing a 20% drop in engine power or any significant change in fuel economy. Something else is going on. You might be falling under the spell of the logical fallacy "Post Hoc Ergo Propter Hoc", which translates from Latin to English as "after this, therefore, because of it". Politicians use this one all of the time to tar their opponents and/or take credit upon themselves. John [ April 19, 2004, 01:28 AM: Message edited by: jthorner ]
 
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23,591
I have a '96 Audi with a 2.8 12v V6 motor. It cranks maybe 0.3 seconds before the motor fires up, regardless of oil type and brand. Oh yeah, I used to use M1 0W-40 and it made my engine sound like a sack of nails. M1 5W-40 works much better in my motor: it's smoother and much less loud. I don't notice a drop in performance or a decrease in fuel mileage. [Cool] If I had to crank for more than a second I'd check the battery and alternator.
 
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7,409
Location
Austin, TX
quote:
Originally posted by jthorner: You might be falling under the spell of the logical fallacy "Post Hoc Ergo Propter Hoc", which translates from Latin to English as "after this, therefore, because of it". John
Dang...them there some pretty highfalutin words. Bet someone learnt you ciphering too. [LOL!]
 
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2,768
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Tn
The simple explanation is viscosity, even in your climate. The 0W-40 has the Starburst also. I believe you, and I have noticed dramatic differences in other vehicles with different formulations. It's not alway vicosity related. In 2.0L engine range, different oils can make a big feel in driveability difference.
 
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1,613
Location
WA
I filled my mothers 01 2.0 Beetle with Delvac 1. She has no problems at all. She lives in Socal. I bought her a case of it. So she will be using it for the next two years.
 
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Location
PHX
quote:
The simplest explanation is usually the corect one
Then you could probably explain how the oil has changed your car's performance....... Sorry, a skeptic by trade......
 

GSV

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696
Location
Utah
IF the T&S 5w-40 is Delvac 1 it is thicker than 0w-40 but I'd have to suspect a vacuum leak or a whacked sensor.  - PS - Cool name [Cheers!] [Patriot]
 
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11,247
Location
PA
My Mom has a 2.0l Passat that was just weaned off of Castrol RX 15w-40 to Rotella T syn 5w-40. VWs like 40 weight synth, no reason to think D1/SUV would be much different. 2.0l is slow anyway, I put heavy Pennzoil LL 15w-40 into a female friend's Jetta, that did not even affect acceleration, made it quiet and smooth. Anyway, D1/SUV is still going into both cars for Fall.
 

TheNauseator

Thread starter
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54
Location
San Francisco Bay Area
"You might be falling under the spell of the logical fallacy "Post Hoc Ergo Propter Hoc", which translates from Latin to English as "after this, therefore, because of it". The simplest explanation is usually the corect one.
 
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1,050
Location
Calif.
But doesn't using 15W-40 make the car waste more gas? I guess the reason you would get better fuel economy with the 0W-40 Mobil 1 is that its Energy Conserving. A non energy conserving like Mobil 1 5W-40 Truck&SUV would make it less fuel efficient. But both oils should not make the car feel a lot different. I have tried 5W-40 synthetic 5W-30 Synthetic and conventional 5W-30 in my 02 VW Jetta GLS 2.0L and don't notice any difference in terms of gas mileage, acceleration. [ April 20, 2004, 12:35 AM: Message edited by: lpcmidst128 ]
 
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39,805
Location
Pottstown, PA
I noticed a cranking issue (not cranking to start) when I switched to Delvac from 5W-30 M1. This is in freezing or sub freezing condtions right after the oil change (in both my 4.0 and 2.5 Jeep engines). Economy on the 4.0 went up for about 7k. The 2.5 has such variable fuel economy that I never can eliminate enough variables to point at any one thing (if you aren't "fuel squeezing" it ..you drop mpg like a lead balloon [Frown] as high as 23 and as low as 13 if my daughter gets a hold of it) I'll buy a "cranking issue" ..that is, it may crank "slower" until it catches...but for the rest I would have to look elsewhere.
 
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Location
White House, TN USA
quote:
Originally posted by TheNauseator: "You might be falling under the spell of the logical fallacy "Post Hoc Ergo Propter Hoc", which translates from Latin to English as "after this, therefore, because of it". The simplest explanation is usually the corect one.
Except, apparently, in spelling! [Roll Eyes] [Big Grin]
 
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1,130
Location
California
quote:
The simplest explanation is usually the corect one.
In which case the simplest explanation is that something other than a minor change in oil characteristics accounts for your claim that "it takes some 20% more open throttle to get the same acceleration". There remains a complete lack of analytical rational which explains your reported findings, and there is a glaring lack of replication of your report by anyone else. John
 
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7,409
Location
Austin, TX
quote:
Originally posted by TheNauseator: The simplest explanation is usually the corect one.
This logic kinda' reminds me of Monty Python and the Holy Grail: Bedevere: Quiet, quiet, quiet, QUIETA There are ways of *telling* whether she is a witch! Villagers: Are there? What? Tell us, then! Tell us! Bedevere: Tell me. What do you do with witches? V: BUUUURN!!!!! BUUUUUURRRRNN!!!!! You BURN them!!!! BURN!! Bedevere: And what do you burn apart from witches? Villager: More Witches! Other Villager: Wood. Bedevere: So. Why do witches burn? (long silence) (shuffling of feet by the villagers) Villager: (tentatively) Because they're made of.....wood? Bedevere: Goooood! Other Villagers: oh yeah... oh.... Bedevere: So. How do we tell whether she is made of wood? One Villager: Build a bridge out of 'er! Bedevere: Aah. But can you not also make bridges out of stone? Villagers: oh yeah. oh. umm... Bedevere: Does wood sink in water? One Villager: No! No, no, it floats! Other Villager: Throw her into the pond! Villagers: yaaaaaa! (when order is restored) Bedevere: What also floats in water? Villager: Bread! Another Villager: Apples! Another Villager: Uh...very small rocks! Another Villager: Cider! Another Villager: Uh...great gravy! Another Villager: Cherries! Another Villager: Mud! Another Villager: Churches! Churches! Another Villager: Lead! Lead! King Arthur: A Duck! Villagers: (in amazement) ooooooh! Bedevere: exACTly! Bedevere: (to a villager) So, *logically*... Villager: (very slowly, with pauses between each word) If...she...weighs the same as a duck......she's made of wood. Bedevere: and therefore... (pause) Villager: A Witch! All Villagers: A WITCH! [ April 20, 2004, 04:13 AM: Message edited by: 427Z06 ]
 
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764
Location
Fairfield County, CT
I've had the exact opposite experience in an '03 BMW 330xi. When changing over to Delvac 1, the engine sounds better than ever, runs smoothly, and has more power, it's like night and day... I think Delvac 1 is another winner, just like GC.
 
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