Oil Choices....

[DAFF]

Is there a difference between the diesel 15w 40 vs the marine branded stuff. Going through the boat for the winter put down and was getting ready to change the oil.
Plan on using the m1 302 oil filter.

What are you using ??

[92SupraComp]

best stuff to use is mobil 1 20w-50 I believe. Has the highest Zinc content... Also full synthetic so you get 2 years out of it and it goes on sale for $32 at advanced all the time...

[michael hunter]

I agree with 92 comp the one you want is Mobile 1 15w50 that weight has the zinc content for the older engines. I change every 50 hours with a Mobile 1 or K&N filter. Some guys are using Rotella T diesel oil be sure to check the zinc levels in the current formula .I read they have lowered the content in the present formula. I buy the oil at Walmart 24.95 for a 5qt jug the filters come from eBay motors. Make sure they offer free shipping or you will pay as much for shipping as the filters.

[DAFF]

Mine is a newer engine with about 100 hours on it. Plan on using a full syn oil, not sure what is in stock in town at Carquest.

[Wylietunes]

Is there a difference between the diesel 15w 40 vs the marine branded stuff. Going through the boat for the winter put down and was getting ready to change the oil.
Plan on using the m1 302 oil filter.

What are you using ??

Diesel typically carries the "HD" designation for high detergent. It has higher levels of cleaning agents which is needed in diesel engines. Marine oils typically have higher levels of moisture and corrosion inhibitors over your hiway use oils.

Im personally a fan of conventional oil, especially in boats and other seasonal use toys. Synthetic oils has been shown to not stay where is should in engines that sit a lot between uses. This can lead to a dry start and increased engine wear.

Also, Synthetic is not a green light to skip regular service and extend its use in boats. All the reasons to change the oil on a regular basis and before layup are still present with the use of synthetic, same as it is with conventional.

Used oil is corrosive, so leaving used oil in during layup is not recommended
oil collects condensation through normal heat up and cold down cycles. These levels can be even higher in the marine environment
Hydrocarbon (un-burned fuel) levels increase with with engine hours. This raw fuel dilutes the oils lubricating abilities.

In 25 years, ive never seen an engine failure due to too much maintenance

[trayson]

My PCM manual spec'd 30 weight oil. I chatted with a buddy that was a Ford mechanic/tuner that knows these engines inside and out and he had me go with 5w-30 that was a synthetic blend. I went with the Ford motorcraft filter.

[TitanTn]

For those that don't know, I'd go with whatever Michael Hunter suggests. He knows his stuff, has been a master mechanic, and has been around marine engines most of his life. His feedback is based on experience and real-world knowledge. This isn't a paid endorsement, but since it's often hard to tell on a forum when you're getting solid info or just opinions, I wanted people to know that michaels statements aren't opinions.

[michael hunter]

Wow Rob that's quite a pedestal you have put me on. I am not a boat guru I learn new things every day from this and other forums . I go with what works and with a 30 year boating history I have found a lot of things that work. That's not to say that different ways don't work. When it comes to oil any high quality oil will probably be fine for newer roller cam engines . The older flat tappet engines require ZDDP to lube the cam. I think 2200 ppm minimum is required. I recommend everyone to do their own research and make their own decisions. Forums are a great way to get information and bad information is usually corrected by someone in the know.

[TitanTn]

Wow Rob that's quite a pedestal you have put me on....

LOL. Yeah, I might have gone a little overboard, but I know there are some new guys on this board that may not know, and I wanted everyone to know that this was more than just an opinion. It's nice to know that someone is commenting based on experience and not because "my daddy always used pennzoil..."

[Cusefan78]

My PCM manual spec'd 30 weight oil. I chatted with a buddy that was a Ford mechanic/tuner that knows these engines inside and out and he had me go with 5w-30 that was a synthetic blend. I went with the Ford motorcraft filter.

I'm a ford guy. I talked to the head mechanic at the ford dealer and he told me ford filters are way better then the parts store filters like fram. He even cut open a new filter and showed me the difference. I was shocked at the quality differences. I used Sierra 24w40 semi synthetic. Talked to skidim and they recommend that or mercury oil.