Questions and a plea for more activity here

[JonS]

I am a boater also. I wish there was more action here too. What i have heard is
1. not to use a multi-grade in a boat, syn or dino
2. Merc 25w-40 is a straight weight
3. use a diesel rated oil for gas engines

I have a PCM 5.0 1992 ford. My manual calls for sae 40 in temps over 50f. I use (in MN) sae 30 ( Delo 400 sae 30) because my oil presures are excellent with 30, and all the dealers use sae 30. I would like to use a multi-grade 20w-50 but was strongly advised not to by many dealers and experts. Also, i felt like if i use 40w, my pressures would be to high. i was also told by a PCM rep not to use merc 25w-40. The PCM's come out of the factory with Castrol sae 40. Sorry fo the jumbled info.

 

[joee12]

I agree with both of you. I was hoping that there would be more activity on this board. I think that marine oil, both 2 and 4 stroke is very confusing. Manufacturers have their brands of oil, cleaners and such, with no product info available. On other boards, I have seen 2-cycle oil debates go on for several hundred posts concerning OEM vs. aftermarket oil. -Joe

 

[twb]

I was really hoping there would be more activity in the boats forum. It would seem to me that the special needs of marine engines would spark some good debates and discussions. What's really frustrating to me is that given my location up north and working too dang much, I never run my boat enough to justify have oil analysis done. If I did I could just do my own experiments and form my own opinions. Oh well.

Merc recommends their own (of course) 25w40 in their I/O engines. This is a conventional oil.
1) Do the demands on a marine engine truly warrant the 40 weight?
2) Is the narrow viscosity range just to get an oil that withstands the demands of a marine engine?

3) Are there any boat operators that get a lot more hours on their craft than me and have oil analysis done? If so, what are the details?

If anyone has any facts/rumors/opinions about what engine oil to use in a marine engine, please chime in!

 

[dragboat]

twb
What year model boat and brand engine is this? I would take it to be a Chevy as posted. Can you tell us how many hours a year it is ran? What type usaege,ski,pleasure cruise,wide open throttle quite often?

If I owned one I would just treat it as a hi performance street engine and looked for a hi HTHS oil of 3.5 or better and SL would not scare me away if proper brand,grade was chosen that meets that HTHS .

If this helps,a Friend bought a new Trisonic with a Ford 302 in 1975 and never used anything but Pennzoil through those years,it was ran hard and had many hours on it but not abused and the motor was in good shape 4 years ago when it was sold. What I am saying here is there are better oils available now than through those years but see how that one held up?,even the same brand is better than before as a result of GF3 and SL but not all GF3 or SL oils will hold up the same
I don't like changing oil on boats so if I were to buy one tommorrow I would look for a HTHS of 3.5 or better and use it all season,change the oil the weekend before the last time out for the season.
Oils of my choice for ski boats with hydraulic lifters with only once per season oil changes because of low time would be

Yamalube 20/40
Shaeffers 10/30 Supreme
Mobil 1 0w40
The Mobil M/C oil "not V -Twin"

Or the new Conventional 15w40 Deisel oils with the SL designation

Possibly Del Vac 1

Not in any particular order just some initial thoughts

 

[JonS]

Dragboat,
What about straight weights? I was on the Mississippi last night with my 302 ford in my skiboat and ran 3500 rpm's for 5 miles. I felt good because i was usung Delo 400 sae30. My oil pressures were 60lbs the whole way. I don't know if i would have felt as easy if i would have 15w40 in there. The 15w scares me. Do multi-grades (15w-40 or 10w-40)leave more deposits compared to straight weights when worked hard or sheared???

 

[dragboat]

Jon I beleive straight wt dino's are near ideal for most boats of this type in warm water or that are warmed up properly before ran hard. Looks like this oil is working well for you.

I think the 15w40 Diesel oils will leave more deposits because of the Sulphated Ash than getting the VII's hit hard. That is much to why I posted the old boat that ran Pennzoil for years,I feel certain the VII's have been greatly improved on since then by "most" all Companies or rather brands.

 

[JonS]

I've heard that multi-grades are to thin (15w-40) and under high load, which is a boat pushing thru the water, the viscosity improvers get squished out and you get metal to metal.

I used to suck the oil out of the dipstick and would measure what i took out, and it was exactly what i had previously put in last time. So i would get all of my oil out. Now i suck it out of a permanent hose connected to my drain. I hook a pump to the other end and in 3-5 minutes i have my 4-1/2 measured quarts.

A boat engine is under much more stress than a can engine. It is like pulling a trailer with no wheels on it. A boat stops as soon as you let upon the gas. This would tell you that there is a huge load.

 

[dragboat]

Jon,when you back off the gas it is the prop drag in the water causing this load you are experiencing with your particular boat drive.The rest will be caused from the lifting strakes let the boat back down in the water causing friction of sorts" breaking surface tension of the water".

Yep,that style you have and a V-Drive will act like one has put on the brakes! Stern Drives like Mercruiser, OMC, Volvo Pents ect will not be quite as obvious

Take a boat with Jet Drive and after full throttle run it will coast far

I personally do not like the idea of not removing all the oil in a change.Seems the residual would eventually catch up. On Lake Racers or inboard ski boats I use just a replacement fitting available that threads into the oil pan drain and has a threaded plug at the end of the hose,then stick it out the boat hull drain plug and let it drain overnite

 

[twb]

Okay, a little bit of a follow-up, including information I meant to include in the original post.

I'm running a 4.3L (190hp) Mercruiser in a 21ft cuddy. We use the boat for pleasure cruising, tubing and skiing (let's not talk about the activities on board when sitting in the middle of the lake

) I spend probably 90% of my running hours between 2800 and 3200 rpm. If I get some nice smooth water I'll do several miles at a crack running at 4000rpm or better and only a couple times a year at wide open throttle. I average just under 30 hours a year. This year I used Schaeffer's 15w40 and plan on using the same when I winterize in a week or so. **** !

JonS (or anyone) - Can you explain why multi-viscosity oil is considered "bad" for a boat?

By the way dragboat, I hate changing oil in a boat too. I'm currently using an oil sucker, and wonder how much old oil gets left in. If I can get to my drain plug, I'm yanking that thing out this year (after sucking out the oil

) and ordering a Fumoto valve with a hose nipple. I hope it comes as quickly as the last one I ordered.

 

[dragboat]

twb
Seems what you are doing is working well for you. I do though think the 10/30 Schaeffers is up to the task with that newer style engine. The oil you chose I guess can be a safty margin of sorts

That type of use would equate to 1800 miles or so at 60 mph in a car on a hiway trip,so I would think even though some stops and starts ect the oil you are using is well within limit of staying in spec as far as not needing replaced