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So it is time to change the oil in the 496 HO. I usually use OEM 25W-40 synthetic blend by Mercury just like the manual states. The store (West Marine) now only carries some crap made by some outfit called "Sierra". So what to do now? Use this or go to Autozone? If I go to Autozone what oil and filter should I pick up? Thanks. Dave
 

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The HMFIC
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I do my own oil changes also. I use mobil one synthetic and a k & n oil filter. Never had a prob doin this. U can order quicksilver stuff on line if ur not in a hurry. Quicksilver is merc.
 

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It's what we do
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Mercury Marine Oil Requirements for Gasoline Engines and Preventing Contamination of Engines with Emissions Control

If Mercury MerCruiser Full‑Synthetic, 20W‑40 oil is unavailable, use the following lubricants, listed in order of recommendation.

If you are servicing a catalyst engine, use these for short periods of time only.

1. Mercury/Quicksilver 25W‑40 Synthetic Blend, NMMA FC‑W–rated 4‑cycle MerCruiser oil

2. Mercury/Quicksilver 25W‑40, NMMA FC‑W–rated 4‑cycle MerCruiser oil

3. Other recognized brands of NMMA FC‑W–rated 4‑cycle oils

4. A good‑grade, straight‑weight detergent automotive oil according to the last row of the operating chart below.

NOTE: We do not recommend non‑detergent oils, multi‑viscosity oils (other than as specified), non FC‑W–rated synthetic oils, low‑quality oils, or oils that contain solid additives.

Mercury Full-Synthetic MerCruiser Engine Oil, 20W-40, NMMA FC-W rated

MerCruiser/Quicksilver 25W-40 Synthetic Blend, NMMA FC-W rated 4-cycle MerCruiser oil

Mercury/Quicksilver 25W-40, NMMA FC-W rated 4-cycle MerCruiser oil
Other recognized brands of NMMA FC-W rated oils


Preventing Contamination of the Emissions Control System

Catalyst and oxygen sensors can become contaminated, leading to component failure. Phosphorus, found in some marine‑grade oils, and other compounds will damage or destroy a catalyst's ability to clean the exhaust. Catalyst‑friendly oil, like Mercury Full Synthetic MerCruiser Engine Oil, prevents this damage. Approved synthetic oils must be used in MerCruiser engines with emissions control.

If you are going to use Mobile One, I recommend the 25/50 for Marine engines.
 

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Mercury Marine Oil Requirements for Gasoline Engines and Preventing Contamination of Engines with Emissions Control

If Mercury MerCruiser Full‑Synthetic, 20W‑40 oil is unavailable, use the following lubricants, listed in order of recommendation.

If you are servicing a catalyst engine, use these for short periods of time only.

1. Mercury/Quicksilver 25W‑40 Synthetic Blend, NMMA FC‑W–rated 4‑cycle MerCruiser oil

2. Mercury/Quicksilver 25W‑40, NMMA FC‑W–rated 4‑cycle MerCruiser oil

3. Other recognized brands of NMMA FC‑W–rated 4‑cycle oils

4. A good‑grade, straight‑weight detergent automotive oil according to the last row of the operating chart below.

NOTE: We do not recommend non‑detergent oils, multi‑viscosity oils (other than as specified), non FC‑W–rated synthetic oils, low‑quality oils, or oils that contain solid additives.

Mercury Full-Synthetic MerCruiser Engine Oil, 20W-40, NMMA FC-W rated

MerCruiser/Quicksilver 25W-40 Synthetic Blend, NMMA FC-W rated 4-cycle MerCruiser oil

Mercury/Quicksilver 25W-40, NMMA FC-W rated 4-cycle MerCruiser oil
Other recognized brands of NMMA FC-W rated oils


Preventing Contamination of the Emissions Control System

Catalyst and oxygen sensors can become contaminated, leading to component failure. Phosphorus, found in some marine‑grade oils, and other compounds will damage or destroy a catalyst's ability to clean the exhaust. Catalyst‑friendly oil, like Mercury Full Synthetic MerCruiser Engine Oil, prevents this damage. Approved synthetic oils must be used in MerCruiser engines with emissions control.

If you are going to use Mobile One, I recommend the 25/50 for Marine engines.
That's AWFULLY thick oil for low-HP engines with oil coolers??? WHY sling that heavy of an oil around??

If that motor was in a 2001-200? GM 2500/3500/4500, it would specify 5w-30 right on the cap.

Mine runs 25psi at idle and 45 at speed. With 10/30. So, obviously there aren't any clearance issues.
 

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It's what we do
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That's AWFULLY thick oil for low-HP engines with oil coolers??? WHY sling that heavy of an oil around??

If that motor was in a 2001-200? GM 2500/3500/4500, it would specify 5w-30 right on the cap.

Mine runs 25psi at idle and 45 at speed. With 10/30. So, obviously there aren't any clearance issues.
Did you see the recommended oil for that engine from Mercruiser? 25/40... not 10/30. There is a reason they don't recommend 10/30. The 496 HO isn't in a GM 2500/3500/4500. That is why you don't see the oil cap with 5w-30 on it. These are not the same engine as a street driven vehicle and see WAY more rpm's and load. The bearing clearances are not the same. 25 psi at idle is low for that engine and I disagree with your clearance thoughts.

The HP range we are talking about has nothing to do with oil weight. It's not about "slinging" oil around. It is about wear and keeping an oil film between those surfaces. Not just the bearings, but lifter bores, piston pins, piston to bore, rocker arms, pushrod ends, etc.

A 25/50 synthetic flows through the oil system with less resistance than a 20/50 petroleum oil. How often do you think a marine engine will see the oil working as a 50w?
 

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How often do you think a marine engine will see the oil working as a 50w?
Very rarely.

20w50 at 212 degrees becomes 10w.

And of course Merc (or any other MFG, for that matter) is gonna recommend/require THEIR brand (or labled) oil! It doesn't necessarily mean it's the best thing for it. It doesn't mean it's NOT, either.

In the clearances - there's just MORE molecules of a smaller (lighter) oil than there would be with a larger (thicker) oil. If you are trying to walk across a floor with ball bearings spread out on it - your feet would roll much easier on 100 small bearings than they would on 10. The more molecules you can stuff into the void, the more cushion there is. AND, more surface to take away heat.
 

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It's what we do
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Very rarely.

20w50 at 212 degrees becomes 10w.

And of course Merc (or any other MFG, for that matter) is gonna recommend/require THEIR brand (or labled) oil! It doesn't necessarily mean it's the best thing for it. It doesn't mean it's NOT, either.

In the clearances - there's just MORE molecules of a smaller (lighter) oil than there would be with a larger (thicker) oil. If you are trying to walk across a floor with ball bearings spread out on it - your feet would roll much easier on 100 small bearings than they would on 10. The more molecules you can stuff into the void, the more cushion there is. AND, more surface to take away heat.
You missed my point in the information completely. It's not the BRAND, it's the weight I was referencing. Mercruiser recommends their brand for marketing and the WEIGHT for engine demands. Again, Mercruiser engines as well as any properly built marine engine has more bearing clearance than a passenger car engine (among other things). More clearance means thicker weight oil, for reasons that would take way too much time and better suited for the "Dyno" section. I am very aware of how oil works, which is why we recommend different weight and type of oils depending on many factors. This comes from over 30 years of building engines for marine and automotive applications.
I'm out. :)
 

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You missed my point in the information completely. It's not the BRAND, it's the weight I was referencing. Mercruiser recommends their brand for marketing and the WEIGHT for engine demands. Again, Mercruiser engines as well as any properly built marine engine has more bearing clearance than a passenger car engine (among other things). More clearance means thicker weight oil, for reasons that would take way too much time and better suited for the "Dyno" section. I am very aware of how oil works, which is why we recommend different weight and type of oils depending on many factors. This comes from over 30 years of building engines for marine and automotive applications.
I'm out. :)
Look. I know you have plenty of experience, or you wouldn't be in the business you are.

The fact is, any THICKER oil than NECESSARY is doing more harm than good. Boat motors don't run everyday like a car does either. So, the thinnest oil that will suffice is what should be used. It will get to the bearings quicker after long term storage and also during EVERY start.

Here is an interesting tidbit of information. A 75W-90 gear oil has the same viscosity as a 10W-40 engine oil at 212 and 302 F. Once again, those numbers on that oil can are misleading and certainly add to the confusion I see among automotive enthusiasts. At 75 F gear oils are much thicker than motor oils.
Again, at normal engine temp, 20/50 is negligibly thicker than 30w. They are almost exactly the same at 212 degrees. So, the thicker oil is only HURTING things during initial startup. Plus putting extra load on the distributor gear and camshaft.

This is not 30 years ago anymore. Oils and parts have come a long way since then. 10psi PER 1000rpm is what it takes to safely run any performance motor. I have 25psi at 800rpm and 45 psi at 4000. Any thicker oil would just be wasting HP.
 

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It's what we do
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Look. I know you have plenty of experience, or you wouldn't be in the business you are.

The fact is, any THICKER oil than NECESSARY is doing more harm than good. Boat motors don't run everyday like a car does either. So, the thinnest oil that will suffice is what should be used. It will get to the bearings quicker after long term storage and also during EVERY start.



Again, at normal engine temp, 20/50 is negligibly thicker than 30w. They are almost exactly the same at 212 degrees. So, the thicker oil is only HURTING things during initial startup. Plus putting extra load on the distributor gear and camshaft.

This is not 30 years ago anymore. Oils and parts have come a long way since then. 10psi PER 1000rpm is what it takes to safely run any performance motor. I have 25psi at 800rpm and 45 psi at 4000. Any thicker oil would just be wasting HP.
I'm out of this debate. At this point I would check out and let you have your way. However, your statements are not correct. Thank you for the calendar lesson. My knowledge is based on today, not 30 years ago.

Your 10 psi per 1000 rpm's has been a blanket statement for longer than 30 years and absolutely does not apply to the marine performance engine. That would mean 7 psi of oil pressure at 700 rpm's idle. Good luck with that.

You refuse to acknowledge the bearing clearance issue. To get right to the point, thinner oil in an application requiring minimally thicker oil will actually be the cause of premature bearing wear.

AGAIN, we are not talking about a passenger vehicle with .0010 to .0015 rod bearing clearance. It is a marine engine with .0020 to .0028 clearance.

Your 30 years ago statement is an insinuation that reminds we why I as well as many other people in this business choose to not offer advice on this website.
 

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Lil' Hellyun
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I'm out of this debate. At this point I would check out and let you have your way. However, your statements are not correct. Thank you for the calendar lesson. My knowledge is based on today, not 30 years ago.

Your 10 psi per 1000 rpm's has been a blanket statement for longer than 30 years and absolutely does not apply to the marine performance engine. That would mean 7 psi of oil pressure at 700 rpm's idle. Good luck with that.

You refuse to acknowledge the bearing clearance issue. To get right to the point, thinner oil in an application requiring minimally thicker oil will actually be the cause of premature bearing wear.

AGAIN, we are not talking about a passenger vehicle with .0010 to .0015 rod bearing clearance. It is a marine engine with .0020 to .0028 clearance.

Your 30 years ago statement is an insinuation that reminds we why I as well as many other people in this business choose to not offer advice on this website.

Yup......right on point!:)
 

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Lovin' IT!
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I'm out of this debate.

Your 30 years ago statement is an insinuation that reminds we why I as well as many other people in this business choose to not offer advice on this website.
Maybe you should just mind you own fricken bees wax, next time! :p
 

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I'm out of this debate.

You refuse to acknowledge the bearing clearance issue. To get right to the point, thinner oil in an application requiring minimally thicker oil will actually be the cause of premature bearing wear.

AGAIN, we are not talking about a passenger vehicle with .0010 to .0015 rod bearing clearance. It is a marine engine with .0020 to .0028 clearance.

Your 30 years ago statement is an insinuation that reminds we why I as well as many other people in this business choose to not offer advice on this website.
For those of you with a stock 496/496HO, the MAIN bearing specs are actually .0011-.0024, other than #5 which is .0025-.0038.

Rods are .0011-.0029.

YOU CAN RUN WHATEVER OIL YOU FEEL COMFORTABLE WITH. I have been running what I run for over 200 hours now with no abnormal oil filter trappings. I definitely run it hard when the mood calls for it, and I am quite certain it would have started putting metal into the filter(s) by now.

As BDMarine says, you can also run it by the book. Your choice. It's a free country.
 

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The Pool Bitch
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Your 30 years ago statement is an insinuation that reminds we why I as well as many other people in this business choose to not offer advice on this website.

I guess I'd better not ask if these pants my my ass look big then I guess. :D
 

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32 DW X-CAT
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Comment:

I run a straight 30W Oil it can be Torco, Valvoline, Amsoil or Eneos it always works for me.

I was under the impression that since I run my motor in moderate climate with virtually no winter to speak of the 30W oil is perfect.

B&D Marine we appreciate your input. However, you understand part of the process here on a public forum is the exchange of ideas. I agree completely with your statement that Marine motors are faaaar [multiple "a"s means really different:)] different than street/truck motors.

It is good to hear from someone in the marine business as your experience carries more weight in my opinion. Also I'm sure you have customers that have their personal preferences when they come into the shop:D;).

Given that I change my oil more than most people [assumption on my part]. Why! because oil is cheap high performance motors are not. One universal oil I found always works great is the straight weight detergent oils this is why I use 30W.

Also high on my list is Amsoil in 15W 40W Marine/Diesel variant can be used in virtually any vehicle, marine, diesel, Rhino, ATV or offroad application with good results.

I like the back and forth exchange of ideas the conclusion/solution/correct answer will usually be self-revealing:):)punch:).

KAP
 

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Why does it have to be so hard? Someone asked about oil. People are free to provide whatever info they want. I guess they're free to try to cram it down throats, if necessary.

I'm not saying what I run for oil is the BEST for EVERYONE. It's just an option that I have found to work just fine. What if someone else wants to try the same thing? Wouldn't they feel better trying it if someone already had and advised them that there hadn't been any negative attributes thus far??

It just gets me how for some people it has to be ONE WAY and no possibility of any other OPTIONS. Especially when there's plenty of info out there to verify these options.

It's really too bad. But, it's the world we live in.
 

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It is what it is
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So it is time to change the oil in the 496 HO. I usually use OEM 25W-40 synthetic blend by Mercury just like the manual states. The store (West Marine) now only carries some crap made by some outfit called "Sierra". So what to do now? Use this or go to Autozone? If I go to Autozone what oil and filter should I pick up? Thanks. Dave
Sierra is good oil. Sierra is Teleflex, and they are probably the biggest marine parts manufacturer on the planet. You probably have Teleflex cables and steering in your boat already.

That being said, I use Mercruiser oils in my shop, just for the reason you started this post. So that someone doesn't come in and say you use such and such oil????? No I use Mercruiser stuff. Is it the best? Probably not, and it's over priced IMO.

I'd recommend the 20/50 in Amsoil. I also like Mobil 1 products. I use Mobil 1 in my Ilmors, and I've been using Mobil 1 in my personal stuff for years. I like sythetics personally. I feel there's more r & d in the product, more shear strength and heat protection also.

Walmart has Quicksilver. Quicksilver is Mercury's product line for non Mercury dealers. Any Quicksilver product is the exact same product as the Mercury product.

If not I'd recommend a good straight 40wt from Autozone if that's where you want to shop.

B&D has the same opinion as I do, a lot of times it's not worth commenting on something so you don't end up in a pissing match with someone.
 

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You who rock I salute you
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I found buying Mercury products from their online/catalog dock store will usually result in a discount code or card arriving in the mail which is nice.
 
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