Any downsides to switching to a 10W-30?

wtd

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2,584
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southwest Mo.
My 98 chevy truck recommends 5W-30 but you can use a 10W-30 if the temp is above 0*F. I currently run 5W-30 Mobil 1. I was thinking of running a 10W-30 synthetic but was wondering if their are any negative aspects to switching to this weight over the preferred 5W-30? Wayne
 
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2,230
Location
SE MI
The 10W will make it move slightly slower to the upper valvetrain/rotating assemblies. Due to tighter tolerances and possibly smaller oil passages in MODERN engines 5W-30 is recommended over 10W-30. If it says to use 5W-20, stick with 5W-30. 5W-20 is already **** thin, and when it breaks down - gets to be TOO **** thin (Motorcraft switched to synth blend 5W-20 because of this problem). High performance Ford modular engine folks all run 5W-30 for their 300-500 horsepower Mustangs/Mark VIIIs/Cobras/T-birds/Crown Vics. Some inside sources state to use 5W-30 over 5W-20 (regardless of what Ford recommends for warranty issues), and NOT 10W-30.
 

Al

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Elizabethtown, Pa
I have used the 10W (Mobil 1) in 8 different vehicles since '96 (4 of 'em new). Really not a cold weather issue with the syn since it pours at I think -49F. I personally believe the 10W is better and possibly will give a little better wear #'s and also possibly be a little more resistant to shear down. Just an opinion though.
 
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349
Location
Quebec, Canada
quote:
Originally posted by wtd: My 98 chevy truck recommends 5W-30 but you can use a 10W-30 if the temp is above 0*F. I currently run 5W-30 Mobil 1. I was thinking of running a 10W-30 synthetic but was wondering if their are any negative aspects to switching to this weight over the preferred 5W-30? Wayne
After some good talks with Bob and MolaKule regarding the industry's practices in making oil, I see no negative side effects in using 10W30 - more so especially when the manufacturer deems that it is okay above 0F. Regards, Oz
 

wtd

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southwest Mo.
Guys, Thanks for the input. I decided to try switching over to the 10W-30 Mobil 1 supersyn and see how it goes. I changed my oil tonight and will have an analysis done in 3,000 miles to see how its holding up. Hopefully my analysis results will be better than when I was running the 5W-30 Mobil 1 Tri-synthetic. Wayne
 
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Oklahoma
WTD, I feel certain you have made the right choice in VI of the oil epecially with the SS oil,Was a synthetic in it before? PS I like those neck of the woods you live at,close to Eureka right? A Bud of mine stopped by yesterday,he has been using the 5/30 All Climate oil in his truck since it was new,,I showed him this board,then showed some copies of various data sheets for cP crank reasons and viscosity at 100 C told him the why's of the 5/30 and EPA and CARB,well long story short,he left me with a check to order 7 cases of Sheaffers 10/30 from Bob. He took my papers to show his friends and relatives the benefits of a good flowing 10/30 full syn or syn blend over a 5/30 dino
 
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263
Location
DFW, TX
quote:
Originally posted by Patman: You'll probably get 1/4 of a MPG less, that's about it.
Patman, I'm curious as to what you attest this 1/4 MPG loss to? The way I see it is that there is marginal difference in vis between the two at 100*F and they are the same vis at operating temp (212*F). I suppose I'd be able to be talked into a small MPG increase in the 5w oil during engine warm-up, but I would doubt that too as the engine is in open-loop mode where ideal MPG isn't being used anyway. I'd really love to see a typical temp vs vis chart on the various grades of oil for dino, group III, and the syn oils.
 
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2,095
Location
IL
It's about .7% difference based solely on API requirements on their test engine. So it is likely even less than 1/4mpg. http://www.infineum.co.uk/information/passenger.html See why this "fuel economy" reasoning is bogus and means nothing to you and I, only to the manufactures selling millions of cars facing CAFE penalties with the EPA's noose around their neck. By the way the reason 5w30 has more (miniscule) fuel economy than 10w30 is because it will shear back more under high stress, providing less drag (and less hydrodynamic protection). [crushedcar]
 

Patman

Staff member
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Oakville, Ontario
In some cases there might not even be a difference in MPG either, so my 1/4 MPG guess would be wrong. On a hot day, in a car that sees longer trips, your mileage overall would pretty much be the same with both viscosities. Where you would see a bigger difference would be in cooler weather, on a car that sees shorter trips.
 

wtd

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southwest Mo.
dragboat, Thanks for the encouragment. I was using 5W-30 Mobil 1 prior to changing to the 10W-30. If the 10W-30 Mobil 1 doesn't seem to hold up well, I'm going to try the 10W-30 Scheaffers blend. This is a nice area. I live about a 2 hours drive from Eureka Springs AR and about a 1/2 hours drive from Branson MO. We have alot of good lakes and rivers to fish in. Wayne
 
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VaderSS, where did you get those percentages? That does not look like any I have seen. The data on the link I posted will give 1.4 if you subract the 3.0 from the 1.6 but remember those arethe SUM of the two tests, you have to divide each in half, so its 1.5-.8=.7%, Whoopidy doo.
 
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2,077
Location
Cordelia, CA
quote:
5w30 is another CAFE oil
Not exactly, just the idea of running it year round.
quote:
This from a 69 Corvette Manual <20F: 5w, 5w20, 5w30 0F - 60F: 10w, 5w30, 10w30, 10w40 >20F: 20w, 10w30, 10w40, 20w40 Notes: SAE5w and 5w20 oils are not recommended for sustained high speed driving. SAE 30 oils may be sued at temperatures above 60F.
This was 9 years before CAFE took effect, so I think it gives a pretty good representation of what is good for an SBC. Note that, basically, they have not changed that much. My 96 Impala manual says 5W30 for all temps and 10W30 above 0F, so the only real difference is that 5W30 is allowed at higher temps, and I'm sure oil has come a long way since then.
 

wtd

Thread starter
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southwest Mo.
I found one negative since switching to the 10W-30 Mobil 1. Tonight when I started the truck up, the startup tapping I occasionally have, was much louder than normal. It kind of worries me. I'm not sure if I should stay with the 10W-30 or go back to the 5W-30. The funny thing is that it didn't make the loud tapping noise this morning when I first started it up for the day. What do you guys think I should do? Wayne PS. The tapping is not from using Fram oil filters. I use AC-Delco UPF52 filters. Its been doing this for about the last 10,000 miles.
 
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2,077
Location
Cordelia, CA
I got them from the document linked in the post I linked to above. Going the other way, and multiplying by the each of the above pecentages, I see my baseline go from 18-18.36-18.612-18.75 or .252 from 10W30 to 5W30. (if I were using whatever they used for their baseline. Granted, those are the maximum values, and I would never notice that minor of an improvement or drop in my mileage.
 

Patman

Staff member
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Location
Oakville, Ontario
quote:
Originally posted by VaderSS: Granted, those are the maximum values, and I would never notice that minor of an improvement or drop in my mileage.
Exactly! 5w30 is another CAFE oil, and I truly believe you'll get less engine wear with 10w30, and have a cleaner engine too.
 

Patman

Staff member
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21,989
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Oakville, Ontario
Wayne, how cold was it out when it was tapping? Probably not very cold, and so there really wouldn't have been much of a difference in viscosity on the 10w30 as there would have been with 5w30.
 
Messages
1,856
Location
PA
quote:
Originally posted by wtd: I found one negative since switching to the 10W-30 Mobil 1. Tonight when I started the truck up, the startup tapping I occasionally have, was much louder than normal. It kind of worries me. I'm not sure if I should stay with the 10W-30 or go back to the 5W-30. The funny thing is that it didn't make the loud tapping noise this morning when I first started it up for the day. What do you guys think I should do?
Your tapping is most likely like mine - as result of running Mobil1. Try a Valvoline or Schaeffers product for one oil change, your valves will quiet down considerably. My 3800 All Iron V6 is now quieter than my friend's ultratechie 3.2L TL [Smile] Well... until I get my exhaust anyways [Big Grin] Cold startup valvetap is something I dislike, and the valvoline solved my problem. I blame the Mobil1.
 
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1,933
Location
Oklahoma
Wayne,I see where you wrote the tapping was much louder than normal,if it was tapping with the 5/30 thats not normal. I cannot see this as oil related but have never run that oil,now suppose if we have ten guys here with that problem and the same roller hydraulic lifter chevy motor I would say change brands; Questions: Has the motor ever been into? How many miles was it ran on Dino How many miles is on the motor Does it come up on fast idle when first started cold? Is this the first time Supersyn has been used?
 
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