Marine (gas) Big Block vs. Diesel Oils

[UNC149]

I've read for hours. I know there is much antidotal comments on here (and everywhere) but I also know many of you are engineers, oil nerds and just **** smart with good seat of the pants data.

As I determine my oil needs for my marine gas engine with a an approx. 330hp 7.4L (fuel injected) but not sure on cam but the original engine was a 1997. This is a newer long block...I get really confused, quickly.

1. Some of you say HD diesel oils of the right viscosity are great. High and zinc and built for HD rpm over long haul then...
2. The next guy says no diesel oils (even if spec'd for gas) in boats as the detergents will foam under the higher (3000?) rpms
3. then there is much discussion of one guy running 30, then 40 then 50 all in various configurations from 30 weight (what my original Volvo Penta spec'd in 1997) to my recent mechanic buddy saying to run 20W50 (VR1) or 25W40 full synth.
4. Next guy says marine engines are all marketing and over priced and no different then HD oils

Holy cow guys...what's a girl todo? So much info and so much discussion. What's the science tell us? When we don't know the rings, pistons, cams on a newer long block? The manufacture didn't give much specs other then what todo (and not) in the first 10 and 20 hours.

 

[fantastic]

Welcome! There is a good reason to use Marine oil. I've read that they are better equipped to deal with water & have more anti corrosion additives. Since you can find just about any grade for gasoline engines the skies are the limit there.

 

[BobsArmory]

You joined in 2019 and this is your first post? WOW talk about a long time lurker! ;-) I know nothing about marine engines so I will be interested in the replies.

 

[UNC149]

Welcome! There is a good reason to use Marine oil. I've read that they are better equipped to deal with water & have more anti corrosion additives. Since you can find just about any grade for gasoline engines the skies are the limit there.

Thx. I should have mentioned I"m freshwater so corrosion is not as a big of deal for me as the salty guys...but to push against your comment. In my area there are NOT many options for marine oils and they all seem to be the same viscosity for either Conventional or synthetic.

When I see one guy saying they've been running Mobile Delvac, or similar for years at a 3rd the price...it catches my eyes for sure!

What else do I need to know?

 

[UNC149]

You joined in 2019 and this is your first post? WOW talk about a long time lurker! ;-) I know nothing about marine engines so I will be interested in the replies.

ahaha...I didnt' even look for my history to see I inquired before. I've owned about 30 cars since then so lots of lurking for sure especially on my way to many old European crap. Always lots of debate there too!

I was very surprised to NOT find a marine sub section here.

Ironically I just had to have the owner/mod help get me back in because the system really didn't like my account from long ago...all good now!

 

[fantastic]

Thx. I should have mentioned I"m freshwater so corrosion is not as a big of deal for me as the salty guys...but to push against your comment. In my area there are NOT many options for marine oils and they all seem to be the same viscosity for either Conventional or synthetic.

When I see one guy saying they've been running Mobile Delvac, or similar for years at a 3rd the price...it catches my eyes for sure!

What else do I need to know?

Pick up 5w-40 Mobil 1 European FS at Wal-Mart.

 

[RDY4WAR]

1. Not all common brand HDMOs have boosted levels of ZDDP.
2. Hogwash.
3. People do a lot of stupid things for illogical reasons. Often times, it's just because they're cheap and using whatever is sitting around, not because they think it's a good choice. Valvoline VR1 synthetic 20W-50 is a much better formula than the conventional version and not a bad overall choice.
4. Marine oils aren't just marketing, but they're not anything special either. The only area they differ in is rust/corrosion prevention where they're required to pass a saltwater test instead of just freshwater. Some oils not formulated specifically for marine applications blow marine oils out of the water (pun intended) in this area, particularly among the boutique oils. For example, High Performance Lubricants tests all of their oils (PCMOs, HDMOs, Euro, Race, etc...) to the tougher 24 hour saltwater test with results better than marine oils in their 4 hour test.

Some HDMOs, such those from the likes of Amsoil, Red Line, and HPL, could easily withstand any abuse your engine could throw at them. They also all contain higher levels of ZDDP along with multiple friction modifiers, a more robust DI pack, more shear stable viscosity modifier (or none at all), and so on. This is in contrast to common brand HDMOs that are typically formulated as cheap as they possibly can and still meet CK-4. (and some fail CK-4)

If you want something you can get at your local Walmart, I would personally pick Mobil 1 15W-50 over a marine oil, especially if you're not taking it out in saltwater anyway. (which I'm guessing you're not being in Ohio) Valvoline VR1 synthetic 20W-50 would be the next choice. If budget isn't a factor, I'd go with something like HPL HDMO 5W-40, Amsoil Premium Protection 10W-40, or Red Line HP 5W-40.

 

[UNC149]

Pick up 5w-40 Mobil 1 European FS at Wal-Mar. Thx. I tend to have plenty of this around for cars I have. Big fan. , is the 5w cold weigh much important when 90% of my boating is better 65-95F? What is unique to the europsec that appeals to big block and marine?

 

[Plumb Bob]

I'd go with Delvac 1 ESP 5W-40. Used in marine engines of all sizes for tens of thousands of hours.

 

[UNC149]

1. Not all common brand HDMOs have boosted levels of ZDDP.
2. Hogwash.
3. People do a lot of stupid things for illogical reasons. Often times, it's just because they're cheap and using whatever is sitting around, not because they think it's a good choice. Valvoline VR1 synthetic 20W-50 is a much better formula than the conventional version and not a bad overall choice.
4. Marine oils aren't just marketing, but they're not anything special either. The only area they differ in is rust/corrosion prevention where they're required to pass a saltwater test instead of just freshwater. Some oils not formulated specifically for marine applications blow marine oils out of the water (pun intended) in this area, particularly among the boutique oils. For example, High Performance Lubricants tests all of their oils (PCMOs, HDMOs, Euro, Race, etc...) to the tougher 24 hour saltwater test with results better than marine oils in their 4 hour test.

Some HDMOs, such those from the likes of Amsoil, Red Line, and HPL, could easily withstand any abuse your engine could throw at them. They also all contain higher levels of ZDDP along with multiple friction modifiers, a more robust DI pack, more shear stable viscosity modifier (or none at all), and so on. This is in contrast to common brand HDMOs that are typically formulated as cheap as they possibly can and still meet CK-4. (and some fail CK-4)

If you want something you can get at your local Walmart, I would personally pick Mobil 1 15W-50 over a marine oil, especially if you're not taking it out in saltwater anyway. (which I'm guessing you're not being in Ohio) Valvoline VR1 synthetic 20W-50 would be the next choice. If budget isn't a factor, I'd go with something like HPL HDMO 5W-40, Amsoil Premium Protection 10W-40, or Red Line HP 5W-40.

Thanks, all great intel. So comparing your comment to "fantastic" above you he suggested 5w40 and you said 5w50. For the big block what do you pick the 50 over the 40? It's worth noting my last oil was 5w40 and my oil pressure is a bit low at idle but pretty good a speed. Would the 50 help this? I've seen others claim a 5w50 will shear down to a 40 pretty quickly. Again, just absorbing what I"m reading...really have no club but trust this gang more then any!

 

[UNC149]

I'd go with Delvac 1 ESP 5W-40. Used in marine engines of all sizes for tens of thousands of hours.

It was the Delvac 1300 Super I read about somewhere else that caught up eye recently (silly cheap) but then I noted Wallyword also has the Mobile Delvac 1 ESP you mentioned too. Any experience with the 1300 and its differences?

 

[JavierH19]

I've read for hours. I know there is much antidotal comments on here (and everywhere) but I also know many of you are engineers, oil nerds and just **** smart with good seat of the pants data.

As I determine my oil needs for my marine gas engine with a an approx. 330hp 7.4L (fuel injected) but not sure on cam but the original engine was a 1997. This is a newer long block...I get really confused, quickly.

Have you ever seen metal in the oil that drained out even fine sparkle? Given its age an oil analysis would be worth doing along with a filter cut if you'd like just to see if metals are normal would be good. Maybe once it has at least 30 hours or more to see where it is.

I've seen 25w-40 have 700-800 ppm of zinc and phos though they would still provide plenty of protection since the hths is high and once the additives are active with heat and film is formed you'd be surprised with how little zinc and phos you need with a steady load and rpm as long as it isn't being lugged hard.

1. Some of you say HD diesel oils of the right viscosity are great. High and zinc and built for HD rpm over long haul then...

Generally true. If you look at marine oils like 10w-30 or 25w-40 they're diesel like though api cj or older.

2. The next guy says no diesel oils (even if spec'd for gas) in boats as the detergents will foam under the higher (3000?) rpms

Could possibly be true for shell rotella as a test showed it to foam more so than limit should allow though i'm not seeing it in the wild but i still wouldn't use rotella. Any other diesel oil is better than rotella.

3. then there is much discussion of one guy running 30, then 40 then 50 all in various configurations from 30 weight (what my original Volvo Penta spec'd in 1997) to my recent mechanic buddy saying to run 20W50 (VR1) or 25W40 full synth.

Loads can but aren't always high. Some are able to change the pitch to prevent too much load on the engines some not. For the most part using the recomended grade is fine. Some spec 30 since they're able to lower load and or have really good oil cooling so the oil doesn't roast. If an engine has a block off plate using a thicker usually recommended though that's usually specified. Sure thicker oils run hotter than thinner but you'd still end up with more viscosity with an uncooled 50 compared to an uncooled 40.

4. Next guy says marine engines are all marketing and over priced and no different then HD oils

About 10% true. A 25w-40 will be more stable than a 15w-40 and they're all going to be group 2 and maybe group 3 for the most part. They should also have more corrosion inhibitors though there are enough in diesel oils and regular diesel oil doesn't corrode marine engines unless more water is getting in than there should be and should be fixed. But at the same time 99% are going to be served perfectly well with a good diesel oil.

Holy cow guys...what's a girl todo? So much info and so much discussion. What's the science tell us? When we don't know the rings, pistons, cams on a newer long block? The manufacture didn't give much specs other then what todo (and not) in the first 10 and 20 hours.

If that 454 was mine I'd be using delvac extreme, delo xsp, valvoline, and a few others in 15w-40. The 5w-40 versions of those are also good like delvac esp 5w-40. I have a lot of warren made mag 1 15w-40 and I'd probably use that too but a boat engine is a bigger and more expensive pain to pull out than an old chevy engine if the worst ever happens though the odds of that are tiny. Vehicle engines live easier lives than boat engines even though vehicles see much more use since it's lighter use.

Mobil 1 15w-50 costs the same as the full synthetic 15w-40's in cost per quart so I'd also use that. 4.5 hths is good for it and it could shear down but it'd likely still be 4.0 or higher. Has a strong additive package and outperforms vr1 20w-50.


I suggest you use 2 stroke oil in that 4 stroke gas engine if you aren't already. Run 1 oz per 3 gallons as I run that without issue and it's extra quiet. Started with 1oz per 5 which had some effect then 4 and now 3. Don't think 1oz per 2 gallons makes sense but I may try it now that I think about it. But 3oz causes zero issues with fuel injector nozzles. Still getting the same 16.7 +/- 0.2 mpg compared to lighter mixes in my sierra.

I run 2 cycle in all my vehicles and the ring lubrication is great. I tested it on a mitsubishi since it can measure fuel in two decimal places on my scanner and the hot idle fuel consumption with no load went from 0.27 to 0.22 before and after. 0.05 gallons per hour on its own is nothing but in terms of percentage decrease at idle that's big. Much smoother and quieter too and I'm using 40 instead of 20 grade. On my gm trucks it only measures one decimal place so it's harder to measure but it runs very smooth and quiet and I thought it was already quiet before. On my direct injected 2021 the pump and injectors are quiet like port injectors now.

 

[paulswagelock]

I have been running boats for over 3 decades. Big blocks, small blocks, outboards, lots of experience.
Stay away from large spread oils like 5wxx for marine use. Long runs at high rpm tend to sheer the viscosity improvers.
Mobil 1 15w50 is a decent choice, available and budget friendly. Delvac extreme 15w40 is a good choice also, as is Delo 15w40 xsp.
Don’t overthink this.

 

[fantastic]

Thx. I tend to have plenty of this around for cars I have. Big fan. , is the 5w cold weigh much important when 90% of my boating is better 65-95F? What is unique to the europsec that appeals to big block and marine?

That's right that your temperature range for your boat use doesn't seem to be an issue & the first "W" rating doesn't need to be a low number. I just mentioned a 5w-40 since they're more common. I agree with @JavierH19 recommendation of a 15w-50 as well.

 

[RDY4WAR]

Thanks, all great intel. So comparing your comment to "fantastic" above you he suggested 5w40 and you said 5w50. For the big block what do you pick the 50 over the 40? It's worth noting my last oil was 5w40 and my oil pressure is a bit low at idle but pretty good a speed. Would the 50 help this? I've seen others claim a 5w50 will shear down to a 40 pretty quickly. Again, just absorbing what I"m reading...really have no club but trust this gang more then any!

If using a common brand off the shelf, I'd go with a 15W-50 or 20W-50. The reason being that you're dealing with a brand that formulates to a price point instead of a performance point. They contain a less shear stable viscosity modifier and more of it. The base oils are not the cream of the crop. When it comes to boutique oils that formulate to a performance point (not all, but many), they tend to use more stable viscosity modifier. Since they also use higher quality base oils, less viscosity modifier is needed. Therefore, a 40 grade in those brands will have about the same film thickness and dynamic viscosity as the cheaper 50 grades off the shelf. There's no harm in using a 50 grade from a boutique brand. With marine use, the engine sees a higher sustained load than in a car so I recommend a 40 grade at a minimum. Valvoline VR1 synthetic 10W-40 would be good but is difficult to find in the US, thus I noted the 20W-50 version.

The point above about avoiding wider multi-grades is only true when referencing common shelf brands. Even then, it's no guarantee the oil won't shear. I've seen Rotella T4 15W-40 shear more than Mobil 1 FS 0W-40 in KRL, which didn't perform stellar itself, compared to say HPL HDMO 5W-40 and Amsoil Premium Protection 10W-40 which hardly shear at all. Among the common shelf brands, it's common for narrower multi-grades to actually be lower quality than their wider multi-grade counterparts of the same series. The reason is because you can formulate the narrower multi-grade much cheaper, with lower quality base oils and VII, and still meet spec. Since those brands are all in a race to the bottom, they happily exploit the lower production cost. You're not getting a better product, you're getting a cheaper one at the same retail price to you.

 

[TnT_M]

It was the Delvac 1300 Super I read about somewhere else that caught up eye recently (silly cheap) but then I noted Wallyword also has the Mobile Delvac 1 ESP you mentioned too. Any experience with the 1300 and its differences?

1300 is semi-synthetic, used to be conventional. The ESP will be synthetic. I have had good luck with the 1300 in my Cummins and wouldn't hesitate to use it.