Is a higher viscocity oil better?

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I'm currently debating on either running 10W-30 or 10W-40 maxlife in my 3800-II next oil change. It is spec'd to run 10W-30, but with the hard driving I do I am wondering if 10W-40 would be more appropriate for me. Is there anyone currently running 10W-40 in their 10W-30 spec'd engine successfully? What harm would this do to my engine and why would I not want to run something so thick? 10W-30 @ 100degC = 10.5 cSt 10W-30 @ 100degC = 13.5 cSt [ July 08, 2002, 03:32 AM: Message edited by: Dominic ]
 

Dominic

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Well the way I see it, the oil isn't thicker to begin with, it simply thins less as the temperature rises (according to the viscocity chart found on this site). I am not sure if that is necessarily a benefit or not though - and am curious if running an oil that thins out less with heat is better [Smile] . 5W60 sounds like a coldweather race grade oil - here in the states I haven't seen anything over 20W50 on store shelves.
 
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Higher viscosity Better for protection but not fuel economy. As the US has about the cheapest gas in the world (but generally appears to be low quality) I don't understsand why fuel economy there is even an issue. The 5W60 is special and very new. I know Penrite are interested in how US sales pan out.. Europe will be strong.
 

Dominic

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Well fuel economy should be important here, but with the majority of the vehicles sold today being SUV's and pickup trucks we can see that fuel economy isn't much of an issue. [ July 08, 2002, 04:12 AM: Message edited by: Dominic ]
 

Patman

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I don't necessarily think thicker equals better protection. You have to have a certain viscosity for a particular engine, if you go too thin it'll just shear back too easily under stress, but also if you go thicker it might not flow properly through the engine either. I'm a big fan of 10w30, I personally think it offers all the protection I need.
 

Dominic

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quote:
Originally posted by Patman: I don't necessarily think thicker equals better protection. You have to have a certain viscosity for a particular engine, if you go too thin it'll just shear back too easily under stress, but also if you go thicker it might not flow properly through the engine either. I'm a big fan of 10w30, I personally think it offers all the protection I need.
Thanks, I'll continue on with 10W-30 then [Big Grin] I did some research and found out the only reason valvoline makes a 10W-40 in Maxlife is for engines that are so bad off 10W-30 will leak through... a bad thought for me [Smile] . Thanks again.
 

MolaKule

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Like Patman, I prefer a 10W30, but in synthetic form. 10W30 has the right temp spread and since it has the least viscosity spread, it has fewer VII's to shear back and sludge. I find it also goes farther before darkening, which I attribute to less blow-by.
 

MolaKule

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csandstate [Off Topic!] I used to live in Florissant, MO. Is that hardware store still along the riverfront there in St. Charles? Used to sell old and new wood stoves. I have a theory about that (golly, doesn't molakule have one about everything [I dont know] )? A rule of thumb for lubes has always been (all other things being equal): a. higher loads, higher viscosity lubes; b. lower speeds, high loads (such as large marine diesels), high viscosty; c. tighter clearances, lower viscosity lubes; d. higher speeds, lower viscosity lubes; e. high speed, high loads, higher voscosity lubes than d. 1. With increased oil change intervals still being pushed to reduce owner operating costs; 2. Oils will load-up with microfine particles and will have to be held in suspension longer. 3. Bearing clearances will have to be larger to allow less wear for longer drain intervals. 4. Oil viscosities will have to increased in order to allow for higher bearing clearances. I base this in part on my son's Mercedes six banger which has to use a minumum of 15W40 for his engine in summer, due to low-tension rings and larges bearing clearances. Does anyone have any info on other Foreign vehicles (especially European) to determine if parts clearances show a trend of increasing?
 
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I like rules of thumb. Or is that rule of thumbs? For me, as a rule of thumb(s), 15W40 in everything, ambient temperature permitting. Fuel economy? I can walk a block for beer 'n cigarettes. The rest I waste on women & drugs. Not necessarily in that order.
 
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That heavier oil myth for better protection has zero evidence backing the claim. Talking about heavier than the engine manufacturer requires slash recommends. It's all typical American thinking of bigger is better so a heavier oil gives superior protection. Someone show us an engine that has failed and another engine lived due to heavier oil use. Firing up the popcorn maker now. slomo
 
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Lots of folks here with high mileage engines running 20wt's. I'll preface this with saying under "Normal" operating conditions where it is spec'ed.
 
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Not me. Besides the point being, what you don't spend on fuel will be wasted on other things. How many here would notice a 1.5% fuel economy improvement. Show me the money if you did.
 

Patman

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Wow, talk about reviving an old thread! I wonder what happened to sprintman, we haven't seen him in years frown It's amazing to see how things change, I no longer am a fan of 10w30 like I was back then.
 

OVERKILL

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Originally Posted by slomo
That heavier oil myth for better protection has zero evidence backing the claim. Talking about heavier than the engine manufacturer requires slash recommends. It's all typical American thinking of bigger is better so a heavier oil gives superior protection. Someone show us an engine that has failed and another engine lived due to heavier oil use. Firing up the popcorn maker now. slomo
Just to break this down a bit further: Heavier oil does give superior protection, if it didn't, GM wouldn't recommend Mobil 1 15w-50 for track use in the Corvette and Camaro, Ford wouldn't have called for 5w-50 in the GT500, GT350, Ford GT or the Track Pack version of the Mustang GT. However Engine oil recommendations are based on intended operating conditions and where the requirement exists for added protection, the recommendation or requirement will typically be revised to reflect that. Ergo, the Camaro specs 5w-30 unless you are tracking it, then the recommendation changes. Ford did the 'ol broad-brush on the Track Pack when it was current, despite being mechanically identical to its 5w-20 speccing GT brother, in calling for 5w-50. Other manufacturers, BMW comes to mind, have attempted to bandaide design issues by going to a heavier lubricant, like the E46 M3, which was re-spec'd for 10w-60 due to rod bearing failures. Daily driving conditions, with a generous margin, are what the testing and manual verbiage are based on. The testing and operating environments are designed to replicate "typical" and thus, using what the OEM recommends in these conditions, is safe. That said, if you buy a non-performance car and start hot-lapping it at Sebring and do manage to push the car beyond what the OEM has tested for, the potential for damage or failure is real. A heavier lubricant than spec'd, in these conditions, would be beneficial, just like it is for those with dual recommendations like noted above. But this does not mean that the benefit extends to operating that vehicle under more typical conditions, in which case you are simply impacting efficiency with no real gain.
 
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