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Best engine oil for 496 HO?

Dirty Daytona

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any opinions on the best engine oil to use in 496 HO? Thanks
 

Wizard29

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Here we go again...

Mobil 1 10W-30 in both of mine. Never experienced a lubrication problem whatsoever. Did chuck a head gasket (not lube related) last year and Namba860 at Offshore Marine did the repairs. After about 150 hours or so on the engine, the original cross hatch marks on the cylinders were still plainly visible.
 

Dirty Daytona

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Here we go again...

Mobil 1 10W-30 in both of mine. Never experienced a lubrication problem whatsoever. Did chuck a head gasket (not lube related) last year and Namba860 at Offshore Marine did the repairs. After about 150 hours or so on the engine, the original cross hatch marks on the cylinders were still plainly visible.
Thanks and which filter do you run?
 

GRADS

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What Mercury suggests....
IMG_0428.jpg
 

Dirty Daytona

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Lol thanks wizard. You truly are a wizard because you read minds
 

spectras only

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Mobil 1 10W-30 is for cars with tighter bearing clearances. 25W-40 is the right viscosity for boat engines with looser bearing clearances, operating higher rpm ranges and loads.If I ran 10W-30 in my 6.2 Mercs, oil pressures will drop low at idle after hard ride. The recommended oil was Mobil 1 10W-30 for my Viper, yet later, Chrysler revised using heavier oil , especially for folks like to run their cars harder.
Boat engines run hard once they're going faster than trolling speed.:p:)
 
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Wizard29

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Mobil 1 10W-30 is for cars with tighter bearing clearances. 25W-40 is the right viscosity for boat engines with looser bearing clearances, operating higher rpm ranges and loads.If I ran 10W-30 in my 6.2 Mercs, oil pressures will drop low at idle after hard ride. The recommended oil was Mobil 1 10W-30 for my Viper, yet later, Chrysler revised using heavier oil , especially for folks like to run their cars harder.
Boat engines run hard once they're going faster the trolling speed.:p:)

That's because Dodges start coming apart and the tolerances get loose after about 3 hours or so. :p

Ultimately, it's a matter of preference, but I've done a lot of research to include a conversation I had with B&D Marine (not sure if he still posts here) in which he told me about an engine oil test Richie Zuhl knew about that was conducted for the government with 600 CI BBC engines. Mobil 1 showed the least wear of all the oils tested.

He also told me he ran it in his Daytona for 4 years. One engine lost a fuel pump and leaned out, ruining the ring seal. He ran the boat for another whole season with the oil being filled with enough fuel he had to drain 1 - 2 quarts each weekend of running. When he took the engine apart to re-ring it, he saw zero bearing damage. Not only were the bearings not damaged, they looked like they were just installed. Could have been reused if needed.

With data/testimony like that from a guy who does marine stuff for a living, I found it pretty convincing. That's in addition to other info I've come across.
 

spectras only

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That's because Dodges start coming apart and the tolerances get loose after about 3 hours or so. :p
Never heard of a Viper engine fail using the M1 10w-30 though. My 72 340 in my new Challenger never gave an issue for 8yrs I've owned it, albeit quality of the rest of the car wasn't as stellar;).Overall, my 68 Barracuda 340, 68 charger 383 and my Jeep Cherokees all had excellent engines, 1990 4.0 6 cyl, 1998 318 and wife's 2010 5.7 Hemi, all had good reliabilities.
 

Runs2rch

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Mobil 1 20/50 v twin is probably the best.
 

LargeOrangeFont

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Mobil 1 10W-30 is for cars with tighter bearing clearances. 25W-40 is the right viscosity for boat engines with looser bearing clearances, operating higher rpm ranges and loads.If I ran 10W-30 in my 6.2 Mercs, oil pressures will drop low at idle after hard ride. The recommended oil was Mobil 1 10W-30 for my Viper, yet later, Chrysler revised using heavier oil , especially for folks like to run their cars harder.
Boat engines run hard once they're going faster than trolling speed.:p:)

I don't think the 496 or small block black Merc motors are really looser than stock. They do build a lot of oil heat though.. I know the small blocks don't have oil coolers.
 

GRADS

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You guys are overthinking it. Just do what Mercury recommends. It's a 496HO not some race motor. This reminds me when I had a conversation with a Mercury guy at a boat show and I was asking about soot on the transom with the 496. He asked me what kind of gas I was running and I said "don't even go there, I'm running Chevron Supreme 91 only"....He says "there's your problem, find the cheapest 87 octane you can find and run that". Sure as shit he was right.:D
 

86Howard

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Joe Gibbs HR1
Only oil I use in a boat engine.
 

LargeOrangeFont

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Ok boys thanks for all the help. I just bought 10 quarts of mobil 1 10W-30 and a Napa filter so that's what I'm going to try!!!!!!

Should be just fine! It’s more important you change it than the brand and viscosity (within reason).
 

spectras only

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You guys are overthinking it. Just do what Mercury recommends. It's a 496HO not some race motor. This reminds me when I had a conversation with a Mercury guy at a boat show and I was asking about soot on the transom with the 496. He asked me what kind of gas I was running and I said "don't even go there, I'm running Chevron Supreme 91 only"....He says "there's your problem, find the cheapest 87 octane you can find and run that". Sure as shit he was right.:D

Yes, 496 & 377 [ 6.2 ] both calibrated for fast burning fuel, ie; 87 octane. Using premium won't do any good other than wasting money because the 555ECM is locked and won't change timing to benefit from premium fuel.
For shits and giggles, I tried to have lower temp thermostats [ knew it won't work but the soot problem popped up in the past on RDP ] and immediately developed soot on my transom. Put the OEM back and soot was gone.
Some people think engineers don't know what they're doing when designing these stock engines.:rolleyes: Having a built engine is a different scenario and lot of variables.;)
 

Blackmagic94

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Well that’s the biggest mistake people make all the time.


They think “high octane” fuel makes more power.


You make the most power on the lowest octane you can run without pre detonation.
 

Kachina26

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You guys are overthinking it. Just do what Mercury recommends. It's a 496HO not some race motor. This reminds me when I had a conversation with a Mercury guy at a boat show and I was asking about soot on the transom with the 496. He asked me what kind of gas I was running and I said "don't even go there, I'm running Chevron Supreme 91 only"....He says "there's your problem, find the cheapest 87 octane you can find and run that". Sure as shit he was right.:D
That's true of any ICE, higher octane is designed for higher compression ratios to prevent preignition.
 

LargeOrangeFont

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Well that’s the biggest mistake people make all the time.


They think “high octane” fuel makes more power.


You make the most power on the lowest octane you can run without pre detonation.

Agreed.

I run 91 because the boat is stored and it takes longer to lose octane.

I don’t notice much difference at all, however the 496s get sootier. with it.
 

Ricks raft

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Amsoil marine. 10w-30 seems thin to me especially down in the heat if the desert.
I use full syn 10w-40 amsoil. Amsoil guarantees better protection than straight 40.
Although at this time running their 25w-40, didn't notice it was semi syn when I ordered it. But It holds higher oil pressure than the 10w-40.
 

CobraDave

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Amsoil marine. 10w-30 seems thin to me especially down in the heat if the desert.
I use full syn 10w-40 amsoil. Amsoil guarantees better protection than straight 40.
Although at this time running their 25w-40, didn't notice it was semi syn when I ordered it. But It holds higher oil pressure than the 10w-40.

I run that 25w40 Amsoil also. seems fine but I wish They made a full synthetic with it. I didn’t want to chance a 10w40. From 25-10w in the desert seemed like a large jump.


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Wizard29

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What a lot of the input above (while most of it is good info) doesn't consider is the actual operating temperature of marine engines is lower. Usually 165 degrees or so versus around 210 for auto applications. A thinner oil won't be as thin in the boat as it would in the car.
 

CobraDave

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What a lot of the input above (while most of it is good info) doesn't consider is the actual operating temperature of marine engines is lower. Usually 165 degrees or so versus around 210 for auto applications. A thinner oil won't be as thin in the boat as it would in the car.

Good point.


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mash on it

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What a lot of the input above (while most of it is good info) doesn't consider is the actual operating temperature of marine engines is lower. Usually 165 degrees or so versus around 210 for auto applications. A thinner oil won't be as thin in the boat as it would in the car.

What the viscosity differences between 200° oil and 240° oil?

With water temp at 140, I can make the oil temp go from 190 to 225 in about 5 minutes. Maybe less

Water temp doesn't move.

Using Delo 400

Dan'l
 

Racey

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Stock Merc motors i've been running Kendall 20w50 GT1 for quite a few years now, no issues. I used to run VR1 valvoline but about 6-7 years ago it got ridiculously expensive for being a conventional oil, looks like the price has come back within reason.

Brad Pen/Penn Grade for all the Brummett Motors.

Merc Filters on Stock stuff, Baldwin on everything else.
 

Wizard29

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What the viscosity differences between 200° oil and 240° oil?

With water temp at 140, I can make the oil temp go from 190 to 225 in about 5 minutes. Maybe less

Water temp doesn't move.

Using Delo 400

Dan'l

Viscosity as it relates to different temperatures depends on the oil. Could be quite a bit.

With your water temp at 140 and the oil at 225, what would the oil temp be if you ran that engine at a 210? Guaranteed the oil temp would be higher and as a result, the oil would be thinner.

A BBC needs only about 7 pounds of oil pressure to lubricate sufficiently, so a drop in oil pressure after a hard run never concerned me.

All personal preference, but I know Mobil 1 has been tested extensively and it consistently shows the least amount of wear. Never knew anybody that had an oil caused lubrication problem running it in a boat or anything else.
 

robby dmax

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You guys are overthinking it. Just do what Mercury recommends. It's a 496HO not some race motor. This reminds me when I had a conversation with a Mercury guy at a boat show and I was asking about soot on the transom with the 496. He asked me what kind of gas I was running and I said "don't even go there, I'm running Chevron Supreme 91 only"....He says "there's your problem, find the cheapest 87 octane you can find and run that". Sure as shit he was right.:D

See you were even over thinking the fuel yourself..until you asked someone.
That is what he did on the oil just asking.. and now you are saying he is over thinking.
Good oil and the correct oil is a plus.
 

Boat 405

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Mobil 1 is great oil. Cheap, easy to find and works great. I've run 10w-30 in just about every river boat I've had for 20 years. Baldwin filters or Napa Gold (WIX) is all I run.
 

Bigbore500r

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Viscosity as it relates to different temperatures depends on the oil. Could be quite a bit.

With your water temp at 140 and the oil at 225, what would the oil temp be if you ran that engine at a 210? Guaranteed the oil temp would be higher and as a result, the oil would be thinner.

A BBC needs only about 7 pounds of oil pressure to lubricate sufficiently, so a drop in oil pressure after a hard run never concerned me.

All personal preference, but I know Mobil 1 has been tested extensively and it consistently shows the least amount of wear. Never knew anybody that had an oil caused lubrication problem running it in a boat or anything else.

I never had a lubrication problem, but my 502 did consume a shitload of Mobile 1 when I switched to their 15w50 synthetic. Now, 502 "MAG" motors (and their VP counterparts) are known to consume oil due to the bores being out of round from the factory, and the piston / ring package they run also causes oil consumption issues. My motor was drinking 1.5 quarts over a 4 day river trip on Mobile 1. Swapped back to Castrol GTX 20-50 conventional, and the oil consumption ceased, almost completely.

I also noticed that the motor used about 1/2 quart a trip on the factory specified Volvo Penta 30w. It also used 1/2 quart a trip running Delo 15-40. Castrol GTX 20w50 - Winner for me
 

pronstar

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I never had a lubrication problem, but my 502 did consume a shitload of Mobile 1 when I switched to their 15w50 synthetic. Now, 502 "MAG" motors (and their VP counterparts) are known to consume oil due to the bores being out of round from the factory, and the piston / ring package they run also causes oil consumption issues. My motor was drinking 1.5 quarts over a 4 day river trip on Mobile 1. Swapped back to Castrol GTX 20-50 conventional, and the oil consumption ceased, almost completely.

I also noticed that the motor used about 1/2 quart a trip on the factory specified Volvo Penta 30w. It also used 1/2 quart a trip running Delo 15-40. Castrol GTX 20w50 - Winner for me

I wonder if that little bit of extra viscosity was enough to keep it in the crankcase?


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Ricks raft

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I never had a lubrication problem, but my 502 did consume a shitload of Mobile 1 when I switched to their 15w50 synthetic. Now, 502 "MAG" motors (and their VP counterparts) are known to consume oil due to the bores being out of round from the factory, and the piston / ring package they run also causes oil consumption issues. My motor was drinking 1.5 quarts over a 4 day river trip on Mobile 1. Swapped back to Castrol GTX 20-50 conventional, and the oil consumption ceased, almost completely.

I also noticed that the motor used about 1/2 quart a trip on the factory specified Volvo Penta 30w. It also used 1/2 quart a trip running Delo 15-40. Castrol GTX 20w50 - Winner for me


Interesting... I've had the exact opposite results. My old 94 454 mag would use about a quart of conventional oil in 8-10 hours, (I don't run wide open for more than a few minutes during a boating day), I switched to amsoil and dropped to about a quart in 30-40 hrs. I've run amsoil in the 454, efi hp500, and currently in a 502(bored), and similar usage about 1quart per season 35-50 hrs...
 

Ricks raft

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Viscosity as it relates to different temperatures depends on the oil. Could be quite a bit.

With your water temp at 140 and the oil at 225, what would the oil temp be if you ran that engine at a 210? Guaranteed the oil temp would be higher and as a result, the oil would be thinner.

A BBC needs only about 7 pounds of oil pressure to lubricate sufficiently, so a drop in oil pressure after a hard run never concerned me.

All personal preference, but I know Mobil 1 has been tested extensively and it consistently shows the least amount of wear. Never knew anybody that had an oil caused lubrication problem running it in a boat or anything else.


I often use mobile 1 when on sale at Costco and don't want to bother to order amsoil. But most of amsoil wear ratings claim they are better...
I think there was a thread on here quite a while back claiming Mobil 1 multi viscosity oils were no longer full synthetic and that government ratings were allowing higher levels of base stock and still be called "full synthetic".
 

Bigbore500r

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I wonder if that little bit of extra viscosity was enough to keep it in the crankcase?


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Maybe. Something worked, whatever it was I just stick with the 20/50 GTX and am happy it stays in there
 
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