What Motor Oil Do You Use?

[Dante04SRT]

Re: What Motor Oil Do You Use?

Bump - I'm curious...

 

[180shabah]

Re: What Motor Oil Do You Use?

Because the additives that "thicken" the oil when hot, wear out over time and leave you with a 5W base oil, which is too thin for a marine engine.

 

[jspringator]

Re: What Motor Oil Do You Use?

Think about how much you would have to use a boat to come CLOSE to the equivalent of 5,000 miles a year. I used to have an old GM diesel and did an oil analysis on it a few times. The TBN (total base number, the condition of the additive package) on my 5 w 40 Rotella Synthetic was still great after 6,000 miles. I think GM recommended a 3,000 interval on these engines, the critical factor being soot control. The point is the additive package is very robust, probably would last several seasons with my every other weekend use in the summer only.

The critical factors in marine use would be fuel (carbed engines) and water dilution, both of which burn off in high speed running. These factors would require change far before the additive package wore out. I like synthetics because of the extra margin of safety and superior flow, although this is probably unnecessary in a marine use pattern.

I am not a mechanic, but my guess is that almost all marine engines fail from overheating due to impeller failure, improper winterizing, or some other failure entirely unrelated to lubrication. That is certainly my experience. If a majority of engine wear occurs on start-up, and a 5 base weight synthetic helps reduce start-up wear, why not use it?

Am I missing something?

 

[Dante04SRT]

Re: What Motor Oil Do You Use?

I am going to do my own oil change this next weekend but to save on cost, I was going to use Castrol GTX 20w-50 and a Quicksilver oil filter.

Will this be suitable for my 3.0 Merc? I really cannot afford "Mercruiser" brand oil right now being 2x the price.

 

[Dakota47]

Re: What Motor Oil Do You Use?

it will be fine Dante, any good 20w50 will work..

 

[Matt S]

Re: What Motor Oil Do You Use?

But when was the last time an auto engine ran up a steep hill at 3500 rpm in low gear for hours on end?

Don, I have always been curious of the oil debate in boats and the general consensus that straight weight, 30 for example, is always sugested over multi-viscosity oils. Aside from the fact we understand that a boat motor sees more continuous load than any truck motor, it also runs cooler than a truck motor (raw water that is) and gets an oil change every 100 hours.

Is this an engineering difference, say with the main bearings having a larger gap than automotive motors or something like that? Or, unlike cars, the oil can get much hotter than the cooling water? Don't get me wrong, I'm all about the 30w if that's what they say. Just an interested gear head here.

 

[Dakota47]

Re: What Motor Oil Do You Use?

Btw, Very nice Thundercraft you have there.. i just sold my 1984 Thundercraft Magnum 16ft with a 60 hp merc. Now i have a Rinker V-180 , same style as yours. here is a picture

pics

 

[Dakota47]

Re: What Motor Oil Do You Use?

Im runnin Penzoil 30W heavy duty with a AC- oil filter.

 

[Jeremy420]

Re: What Motor Oil Do You Use?

I have a 90 3.OL Mercruiser and I run Mercruiser 25w40 and a Mercruiser filter when I can.. If not I use Straight SAE 30Wt oil. Last time it was the Valvoline SAE 30.. That's what my manual suggested, I will look into the 40 weight suggestion listed earlier because I rarely use it below 75 deg. outside temps (maybe that was for a bigger sized motor)

As far as Oil Filters.. I know that the marine Mercruiser filters flow twice as much as car filters. Typical car filter between 6 and 12 GPM.. Marine filters run between about 20 - 30 or so... When I don't get a Mercruiser filter I will get a Sierra marine filter 18 -7824 that napa can order for you or their 1069R racing filter that flows 30 GPM!!

The big thing you want in a filter is high flow because you run full throttle, Mercruiser does not publish the specs for thier filters as to make you buy from them.. The sierra marine filters are supposed to be equal to the Mercuiser filters and they won't release the figures either but I am sure they are high flowing.

I have heard that Fram are the worst, also other car filters that will cross reference the OE will likely not be high enough flowing like the Napa cross to a 1086 or 1069 but these two only flow 11 GPM the 1069R Racing filter is the way to go there.. make sure you get at least 20 GPM flow with your filter to be safe..

 

[jimmbo]

Re: What Motor Oil Do You Use?

For the first 2 years I used Volvo synthetic SAE 30. I then switched to Royal Purple 30. Last year I switched to Royal Purple SAE 15 - 40. I am presently using Baldwin oil filters.

 

[watermellonI]

Re: What Motor Oil Do You Use?

Mobile 1

 

[riverjet502]

Re: What Motor Oil Do You Use?

GTX 20-50 dinosaur oil, A/C oil filter. 10 qt pan, modified Gen VI 502...

 

[Bry21317]

Re: What Motor Oil Do You Use?

I am new to I/o Motors. Only had the boat about 2 months, how often do you change the oil?

I did already buy the manual, and it states like 50 hours or something more than that. I have only put like 7 hours on the motor, from the hourmeter, which I have been out alot, but I guess we do cruise and then hang out in the coves alot.

I just figured I would post here and ask this, the engine only has 152 hours on it, and its a 94 Mercruiser/Chevy 5.0 2bbl Alpha 1 Gen 2 Drive.

Thanks,
Bryan

 

[Jeremy420]

Re: What Motor Oil Do You Use?

I am new to I/o Motors. Only had the boat about 2 months, how often do you change the oil?
I just figured I would post here and ask this, the engine only has 152 hours on it, and its a 94 Mercruiser/Chevy 5.0 2bbl Alpha 1 Gen 2 Drive.

Usually every 100 hours.. but 50 would be fine.. better safe than sorry, just check on the condition of the oil.. you can tell when it starts to get blacker and burnt. It's good to check the oil regularly anyway - like once a week to be safe..

It sounds like a great boat man.. low hours.. Make sure you use a marine filter - you need high flow for that 5.0

 

[Manipulator]

Re: What Motor Oil Do You Use?

I've used auto filters for years in boats. I wonder if it's true that the marine filter allows more flow. Oir pressure has always been fine with my boats.

 

[180shabah]

Re: What Motor Oil Do You Use?

I've used auto filters for years in boats. I wonder if it's true that the marine filter allows more flow. Oir pressure has always been fine with my boats.

Pressure and flow are different. The Mercruiser filter does flow almost twice as much as a Fram filter, Whether or not that has any real world benefits, I couldn't tell you. However using a high flow filter(that doesn't skimp on filtration) does offer some piece of mind. I use the K&N oil filter primarily because I can get it locally and also because it tested equal to the merc filter for filtration and marginally higher in flow rate. This can't be said of thier air filters though, you will never see one of them on my vehicles.

There was a great test a few years ago comparing the effectiveness of different brand oil filters for marine engines, unfortunately I lost a bunch of my saved links in a HDD failure at the beginning of the year. As soon as I find it, I will post the link so every one can read it.

 

[Manipulator]

Re: What Motor Oil Do You Use?

Thanks for clarifying. I oftened wondered what the difference was. Still, I'm going with the ol cheapo Wal-Mart Super-Tech ST16 and Super-Tech 30W oil. Been using it for years.

 

[Rob454]

Re: What Motor Oil Do You Use?

Thanks for clarifying. I oftened wondered what the difference was. Still, I'm going with the ol cheapo Wal-Mart Super-Tech ST16 and Super-Tech 30W oil. Been using it for years.

Thats what i use. wally world Super tech oil and oil filters. ive used them in my trucks for about 10 years now without any problems.

So whats the deal? I looked at the owners manual and the repair manual and they both state 40W. now the owners manual was written back in 89. shoudl I go to 40W or should I go to a synthetic oil? I dotn think the filter makes a difference one way or the other. my oil pressure is the same no matter what filter i used.
Rob

 

[Ryan00TJ]

Re: What Motor Oil Do You Use?

I've ran Mobil Delvac 1300S 15W-40 in two 400hp Marine SBC so far with great results. Last 360ci had 362hrs of high rpms and when torn down for a better motor looked new. It also had very low leakdown test numbers. I change the oil every 25 hrs usually. It's actually a PIA as it's every over week as much as I use the boat. Belive it or not I use Motorcraft diesel truck filter on my remote mount setup as they are a good filter and it holds a qt of oil by itself. I also have an oil cooler that keeps the oil right in the 190-220 degree oil temp range when running. 8qt oil system keeps everything well lubed.

 

[tic]

Re: What Motor Oil Do You Use?

Is there such a thing as "bad" motor oil these days?..... I submit that a properly maintained engine will run just as long (or almost as long) assuming dino oil regardless of brand.