Oil change / Type

Hello,

I just bought a 95 prostar w/ the 350 corvette engine (LT-1)..... On the oil cap it says "special oil required" however, the guy that sold it to me, as well as the corvette engine manual states that 10w-30 should be used..... is there a marine grade oil I should be using? or is 10w - 30 okay..... it is after all a car engine right?

Thanks for any help,
Brett

Brett,
10W-30 is would work fine, but I would use a synthetic just because boat engines run at higher RPMs for long lengths of time. But I don't want to start the whole synthetic vs reg. debate. Just be sure to use a good filter such as wix or NAPA(wix makes napa), stay away from FRAM though, if you cut one open you will see why.

(Message edited by skibum*69 on August 30, 2004)

In blind taste tests, 9 out of 10 towboats agree:

Mobil 1 oil, filter, ATF, gear oil.

Jury's still out on wheel bearing grease. I'm sure that not all of the above are the BEST in class, but they're all GOOD, readily available and for sure, much better than most 'marine' fluids/filters.

I suggest 15w-40 marine grade synthetic.

Don't ask a marine mechanic, they'll push their own 'juice', usually Merc-crap petro.

Just asked my mechanic this exact question last Friday. His answer: any good quality 10W-40.

http://www.micapeak.com/info/oiled.html
im gonna go with a hd straight 40 wt. probably rottella by shell

My Ford PCM GT-40 uses straight 40 petro based oil. A friend builds gearboxes for motorcycles told me that synthetics work well in cars because of their superior cooling properties but are slightly inferior when it comes to lubrication. He recommends to stay with petro based lubricants if cooling is not an issue. Multigrades work well if you do not take the time to let the motor warm before taking off. I have a 15 minute idle to fast water so I use straight 40 wt. Manufacturers have a difficult time trying to determine how people will operate their equipment so multigrades are typically recommended to satisfy the masses.

The general public tends to over analyze oils and which to use for standard gasoline engines. The manufacturers marketing groups post information which propogates this confusion in hopes you will buy theirs.

The bottomline: Due to tighter bearing clearances in these later model engines a thinner weight oil is recommended especially in colder regions. Any synthetic will give you reliable performance over conventional. RPM kills oil vicosity as it breaks downs it lubricating properties. But this break down is usually in conjunction with heat. Most boats run in the 165-180 area which is quite cool. Pick one that is easily obtainable and at price that suits your budget. Do not over complicate your life with oil choices.

Filter choices is subject to opinions but I highly recommend that you stay away from Fram Filters...Wix filters are very well made. I have cut open many many oil filters.

I don't know if it applies to boats, but my corvette (97) requires "special oil". Basically what they mean in my case is synthetic. GM has their own, but I use Mobil 1. To make sure, I would call your dealer as well.

If in doubt, it won't hurt to use a quality synthetic. Don't forget to use a quality filter too.

I have the a PS 205 with a 350 in it, it's not the LT-1. I use Pennzoil 20w-50 which is what the manual calls for. I change it every 50 hours or less so I don't have a need for synthetic.

wow...I thought that most all engines made in the last 5 years (from indmar anyway) required (or at least recommended) 15w40. My 1999 and now my 2004 manuals both call for 15w40. Is that wrong?

Bo,
15W-40 is a solid universal oil weight that covers quite a broad spectrum of climates. If you switch to synthetic use 5w-50.

The the MC Owner's Manual calls for 20w50 in the LT-1.

Todd

How often should a boat's oil be changed? after how many hours? on this topic, assuming all is running well on a wakeboard boat, how often should the boat be serviced?

change oil and filter every 50 hours

change transmission fluid every 100 hours

lube cables once a year

The Sequoia and Epic require 5W-30. I've heard that many cars are now requiring 0W-30 for emissions reasons.

Our boat's service interval is officially 200 hours or 12 months. I stick to the latter, in the fall, including ALL fluids, filters and the impeller. Overkill on the part of the tranny, v-drive and impeller, but who said, "if it's worth doing, it's worth overdoing"? ATF and gear oil is pretty cheap and only represent an extra 20 minutes or so altogether. Impeller is not cheap, but is not something to mess around with, ya know?

Can anyone tell me why Mercruiser specifically says NOT to use synthetic?

http://www.mercurymarine.com/fueloil_recommendation_faqs

Could it be because Mercruiser doesn't have a synthetic and doesn't want you to leave the stable? Just wondering.

If I had to make a guess, it is because they want you to buy their oil exclusively. There is absolutely no reason that you can not use synthetic engine oil.
Another reason may also be that it is an old webpage and they have not updated it recently. I saw a lot of reference to early engines and synthetic oil did not really hit main stream use until late in 99. It is now standard on most new cars. I have to say, after 1/4 mile drag racing for many years, a SBC is a SBC. Standard marine motors like what is installed in our boats do not use "Marine Special" internals. The engine is built by GM and ship to Merc to have some special add on's which are mostly be external items. The long block is the long block. So with that said...why could you not use synthetic. I ran mine for 5 hours, then yanked the oil and run synthetic and will. I did the same with my truck.

Like my post above stated, Marketing people make oil choices confusing so you will buy theirs.

Hope this helps

i put synthetic in a motorcycle and it made the wet cluch too slick to work. that sold me. it is definetly slicker than regular oil.

My understanding of why manufacturers tell you not to use Synthetic is because of drain interval. Merc is probably afraid you'll extend the drain interval if you use synthetic. Alot of synthetic oil companies will claim you can extend the drain interval.
I use synthetic after break in but still change oil at 50hrs. I wouldn't prolong the drain interval just because you're using synthetic oil.
The oil still gets dirty.
For me it's worth the extra $20 twice a year to run the best oil I can.

Tom, I heard that somewhere else, too. Mom had her MBZ running synthetics years ago because the tech told her it'd go 10K easy. Agree that it still must absorb all them combustion products and even moisture. I am on a 5K cycle in the Sequoia with the Mobil 1 just cuz it gets pretty expensive doing it at 3K. Spare no expense in the boat, though ;-)

Page 26 of my Correct Craft Manual states:

Synthetic engine oils are NOT recommended for use in PCM Engines. Synthetics may offer advantages in cold temperature pumpability and high temperature oxidation resistance. However, synthetic oils have not proven to provide operational or economical benefits over conventional petroleum based oils in PCM Engines. Their use does not permit the extension of oil change intervals.

It states to use any SAE 15W-40 "SJ"

I change my oil every 50 hours and have been using Mobile or Valvoline.

For what it's worth??
under warranty notice it states:
PCM Engines reserves the right to refuse warranty on part(s) and/or engines damaged by using improper fuels and engine oils.

yea, the way i see it, if you change it at 50 hours, on a long term basis you will probably receive NO benefit from using synthetic oils. It won't hurt anything, but the specific advantages in synthetic oils (less heat breakdown especially) are not taken advantage of in marine engines.

Jeff, one thing I do know is that you are NOT supposed to use synthetics at any period in the first 20 hours of engine use. This is due to regular break-in period "finalizing" of engine parts such as crankshafts and cylinder walls. Small imperfections, nicks, and mishoned metal is generally worn down in the first 20 hours of engine use. Companies specifically put dino oil in engines when new to enable this process to happen. Synthetic oil, due to its superior nature, would often let these small intolerances remain. Otherwise you can have lifelong engine problems with piston ring seating/sealing, valve seating, and crankshaft tolerances. Just what i've read.

Tom,
I have heard all that information as well. Again this really boils down to what you want to believe from the various oil makers. I have used synthetics now for the last 8 or so years in every vehicle and boat I have owned. I change the oil in my diesel pick up truck every 12k miles. I change the oil in my wifes car every 7500. I have never had any issues with ring seating and valve guide wear. Remember there still remains a divided group on oils to use. The old school(as I will term it) still believes in detergent oils and changing them every 2500- 3000 miles, the new school is all synthetic and change them at 5000 - 7500(or longer if they have them analyzed). They key is that you change oil filters at the specified intervals. You cannot extend oil filter changes IMHO.

Engines now are built much differently than years ago. It used to be you had to run the engine 15 minutes at 2K rpm to seat the rings and such, Now you fire them up and go. It used to be you ran the motor and re-torqued the heads, now you fire them and never look back. There were times where makers wanted you to roll your valves at certain miles, now most are not even serviceable.

To me it is more important to understand the design concept of synthetic oils. They were not developed so consumers would get longer motor life using synthetic oils(although it has been proven they do). They were developed to decrease the amount of strain on the environment by the ever increasing demand for fossil fuel/petroleum products. I am just doing my part.

I will run my oil for a season or no more than 100 hours, which ever comes first. I will change the filter at 50 hours.

here here Jeff, GO AMSOIL, to hell with manufacturers recommended intervals. Synthetics have and will continue to prove themselves not only in everyday use but in racing that produces far advanced wear and tear compared to even boat engines. 3000 mile car and 50/100 hr (depending on the make) boat intervals with petroleum based oil keep the oil and oem manufacturers rich so go ahead and make em rich ill stick with my extended intervals ive been doing for over 15 yrs now.

Bob,
I agree. I guess here is a larger question for the followers of this thread. If Synthetic was not the future then why have all the manufacturers of standard detergent oil added synthetics to their product line with a SAE rating that states it "Exceeds" the standard detergent oil. Because they know that sometime soon that it will become a mandate and soon all automotive and marine engines will come standard with synthetics. For now the OEM businesses get rich telling all the consumers to change the oil at 2000-3000 miles or 25-50 hrs. Thats alot of oil being dumped somewhere. I have seen friends change oil that as it is being drained it looks nearly brand new. They say "Well I have 2500 miles and the manual states change every 2500-3000 miles"

I am merely trying to make a point that we all need to do our part. I still say that with proper oil filtering oil can last a lot longer.