Will Thinner Oils Damage Your Engine?

[SZR48207]

Thinner oils do not reduce startup wear, a thinner oil never reduces wear unless the thicker oil is too thick to be pumped. MOFT reduces wear and a thinner oil always has a higher MOFT.

OK so I won't buy 0w30. But I can use 10w30 in warmer months (here in OK) and it would be no worse than 5w30?

 

[aquariuscsm]

Startup wear is and was always just a myth. With all these auto start/stop vehicles they're making now, hell,they wouldn't make it around the block without the engines falling to pieces if startup wear actually existed.

 

[350Rocket]

Startup wear is and was always just a myth. With all these auto start/stop vehicles they're making now, hell,they wouldn't make it around the block without the engines falling to pieces if startup wear actually existed.

I think it exists but it's nowhere as bad as it's always been made out to be. Especially with modern oils.

 

[gfh77665]

OK so I won't buy 0w30. But I can use 10w30 in warmer months (here in OK) and it would be no worse than 5w30?

Thats right. In OK the 5 or 10 don't matter in the summer. I ran SAE 30 an even SAE 40 in the TX summer and my truck never noticed.

 

[BlakeB]

Startup wear is and was always just a myth. With all these auto start/stop vehicles they're making now, hell,they wouldn't make it around the block without the engines falling to pieces if startup wear actually existed.

Nice! As an former Pentastar design engineer I am slightly bias but the engine is really high quality. Few points from the development using tens of millions of dollars in analysis and testing regarding the oil and durability.....

The lighter oil was chosen mostly for fuel economy BUT engineering is the science of compromise. You help one thing but hurt another.

A thicker oil will reduce timing chain and tensioner wear because the center timing chain idler doesn't go fully hydrodynamic till about 1650rpm on 5w-20. So, a thicker oil will lower that number slightly and with general loads/speeds the engine spends a lot of time around 1500-1750 rpm with the 8 speed. So thicker oil is a win there. Additionally, the earlier engines had what was called the "McDonald's Arches" in the idler bearing which was intended in making a more uniform distribution but in actuality acted as a knife edge. This design was changed around 2014 to a smooth bearing. So overall timing chain issues will likely follow the 2011-2014 engine years more than 2014+.


Where you lose.... The head is very complicated with a Type II valve train. Meaning lots of things to pressurize and pump up at start up. A thicker oil didn't do so well here (on long sit times +cold start) and contributed to a overall increased engine wear especially in the head and cam bearings.

Last point. This engine needs occasional WOT runs if you want it to last. Granny cycling is bad for it. So bad for it we actually created a new granny cycle test during the cylinder #3 misfire issue. The highest wear is in the valve guides, because of tight valve stem seals (for emissions, reduce oil burn). They basically dry out. When you go WOT/high rpm/load you get some fresh oil in there and this keeps the wear down. Thicker oil might not help this condition but we also change the valves/guides/seals in 2014+. Not sure the impact.

Cheers!

Kevin


PS. Turn off stop start and do not run e85 if you are concerned about engine wear. Eats the engine alive.

i wish I had some more data for you 2015_PSD,

Unfortunately I left the company as the Gen II was kicking off. I do know the engineering team was VERY nervous on the 0w-20 stuff and it was 100% for fuel economy. My personal opinion knowing the bearing surface area would not have gone up because of the cost I would go up a notch in weight. Not a lot of downside for the margin. Also, we are designing for 150-200K max, not 200k+ so that is always something to think about when OEM's make recommendations.

I would like to note there was this bearing coating they started using called iROX which was very impressive at the microscopic and testing level. It had to go on the front and back bearings to pass Stop-Start because of wear and was very expensive. They likely added that to the rest of bearings to make them work but I don't know for sure, I will have to ask. Regardless, the bearing surface area did not likely increase so from a basic physics point of view your hydrodynamic response to "filling it with water" as we called it will not go in a safer direction at lower rpm.

 

[madeej11]

That depends on which 5w-30 and 10w-30 we're talking about. A 10w-30 will typically need less VII and can make use of thicker base oils which usually means a better HTHS and lower NOACK.

From what I've seen in the few that I have checked they are usually equal hths figures. Petrocan supreme synthetic, 5w30 3.2, 10w30 3.1. Amsoil SS, 5w30 3.11, 10w30 3.11. Amsoil SS MaxDuty Diesel, 5w30 3.5, 10w30 3.5. Those are a few of the ones that are transparent enough to publish hths numbers.

 

[OilUzer]

Startup wear is and was always just a myth. With all these auto start/stop vehicles they're making now, hell,they wouldn't make it around the block without the engines falling to pieces if startup wear actually existed.

From Castrol website:

Castrol MAGNATEC.
Castrol MAGNATEC and its intelligent molecules will protect your car's engine during the critical warm up stage when up to 75% of engine wear occurs. For instant protection from the moment you start.

btw, i like Magnatec and just pointing out what they say.

 

[MolaKule]

Did 20W20 Mineral oil damage my dad's 1954 Buick with it's 322 cu. in. V8?

No.

 

[750IX]

The automatic start/stop isn`t active until engine is at operating temperature, at least on my 2013 Bmw. Anyway i coded it away because i dont like it.

 

[Simon_G]

What will the 40 grade accomplish that a 20 won’t?

You might ask Mercedes that.

 

[Simon_G]

Larger spread oils often shear more losing their viscosity easier.

That's largely a function of the polymers used to boost the VI.

Spend more, get less shear; go cheap, get shearing.

 

[demarpaint]

Case in point: my gilfriend has a 2018 camry 2.5l that spec'd for 0w16. That transmission does absolutely everything in its power to keep the rev's down, it will even upshift by itself in manual mode. Lower rev's = sufficient low HTHS protection. It was so bad that toyota had to release a transmission software update to correct "jumpy" starts at low speeds.

You got me thinking........ Over the years I've been in a few cars with 9 speed ZF automatic transmissions that actually lugged themselves. I'd be running something that offered better HTHS protection in those low revving engines than the 20 grade the mfg. called for to hopefully offer better bearing protection. Especially if a re-flash couldn't rectify the lousy shifting programmed into the transmission

 

[IndyFan]

Startup wear is and was always just a myth. With all these auto start/stop vehicles they're making now, hell,they wouldn't make it around the block without the engines falling to pieces if startup wear actually existed.

@BlakeB nailed it. So the correction is: If it wasn´t for start-up wear, they´d make it the equivalent of around the moon and back, probably 3 times or more before wearing out.

To the original question, regarding the Pentastar tear-down after it finally failed after 625k miles: It ran primarily on Valvoline 5w20. I´m sure that it would have made it to 626k miles if he had run a thicker oil, so the answer is yes, thinner oil causes more wear.

 

[RDY4WAR]

From what I've seen in the few that I have checked they are usually equal hths figures. Petrocan supreme synthetic, 5w30 3.2, 10w30 3.1. Amsoil SS, 5w30 3.11, 10w30 3.11. Amsoil SS MaxDuty Diesel, 5w30 3.5, 10w30 3.5. Those are a few of the ones that are transparent enough to publish hths numbers.

Look at the KV100 compared to the HTHS.

Petrocan Supreme Synthetic 5w-30 ---- KV100 = 11.3 cSt, HTHS = 3.3 cP
Petrocan Supreme Synthetic 10w-30 --- KV100 = 10.2 cSt, HTHS = 3.2 cP

The 5w-30 is definitely shearing more than the 10w-30. If the KV100 were equal, the HTHS of the 10w-30 would be higher than the 5w-30.

Amsoil SS 5w-30 ---- KV100 = 10.3 cSt, HTHS = 3.11 cP
Amsoil SS 10w-30 --- KV100 = 10.0 cSt, HTHS = 3.11 cP

Same deal.

Amsoil SS MaxDuty Diesel 5w-30 ---- KV100 = 12.0 cSt, HTHS = 3.5 cP
Amsoil SS MaxDuty Diesel 10w-30 --- KV100 = 12.1 cSt, HTHS = 3.5 cP

Those 2 are pretty much the same, but it's also a boutique diesel oil using pretty stout base oils in order for both to reach the 3.5 cP HTHS.

 

[Wylie6G72]

When I see someone pour M1 0W-20 into a Porsche 992, I'll consider using it.

 

[kschachn]

When I see someone pour M1 0W-20 into a Porsche 992, I'll consider using it.

Porsche C20.

 

[RDY4WAR]

I can't find anything on the oil grade for Ford's 3.7L V6 outside of North America. My wife's 2012 Mustang 3.7L V6 says 5w-20. Here's a recent UOA on it at 6,800 miles using Pennzoil Gold Syn-Blend 5w-20. I don't really think a 30 grade would improve these numbers at all. I think the only thing a 30 grade would do is drop the fuel economy by 0.5% or so.

2012 Mustang V6 UOA

 

[Astro14]

BuickGN and I were always proponents of thicker oil.

I think he was banned..

He was not banned. He still has a user account.

Folks, this thread has led to some serious bickering, even led to harassment across threads.

Discuss the topic. Stop making it personal. Or it gets locked.

Thanks

 

[Zaedock]

He was not banned. He still has a user account.

If memory serves he was (a couple years before you joined) and was then let back in and then something happened where he didn't want to come back. Either way, it's been too long to worry about it. He was still a cool dude and had a 10 second Grand National.

BuickGN had some interesting thoughts on the validity of UOA's in regard to engine wear. If you guys search though his posts, I believe he had a UOA that looked OK taken from an engine that had a piece of piston in the oil pan.

 

[OVERKILL]

If memory serves he was (a couple years before you joined) and was then let back in and then something happened where he didn't want to come back. Either way, it's been too long to worry about it. He was still a cool dude and had a 10 second Grand National.

BuickGN had some interesting thoughts on the validity of UOA's in regard to engine wear. If you guys search though his posts, I believe he had a UOA that looked OK taken from an engine that had a piece of piston in the oil pan.

He had a UOA from his engine that was perfectly normal, yet it had no bearings left in it, IIRC.