MerCruiser oil specs

[Misty IV]

My owner's manual calls for the MerCruiser spec 25W-40 oil. Ironically, Mercury Marine is the only 25W-40 out there. I'd like to run a synthetic oil in my engine, with the amount of hours it is running and trolling on the water. Other name brand oil manufacturers offer 20W-50 & 15W-40 in synthetic. I understand the differences in the numbers (been a motor head since I was 10 years old or so). In a marine application, will running a 15W make any difference than a 25W, other than the thickness of the oil when it is cold? I read somewhere in the MerCruiser manual that if an engine failure occurs due to a non-Mercury spec oil, the warranty will be voided. What does everyone else run in their MerCruiser engines these days? My engine is the 4.3L V-6.

[Jack]

http://www.bobistheoilguy.com/cms/index ... e&Itemid=1

Some interesting reading on oil if your bored. I always try to run an oil with a FC-W rating.

[rustyrat]

I run MerCruiser spec 25W-40 oil. Works fine for me.

RR

[HPORT]

If it's under warranty and they call for a specific oil to honor the warranty, then you run it till it expires, then run 20w-50. Synthetic is better then regular oil in most respects, but the important part is that its the correct weight, rating and changed regularly on a specified PM scheduled. To get the best out of your oil, make sure your engine thermostat is working correctly and the engine can get to operating temperatures.

I just dropped a brand new Mercruiser 5.7L in, it only requires that you use the correct weight and rated oil for operating conditions and proper oil filter ( it came with Quicksilver filters), and that you change the oil and filter on a typical service interval after the initial break-in period.

John

[jimski2]

Boats are not operated in below freezing temperatures so low viscosity oils are not needed to start the engine. Mercury is playing it safe by requiring the 25 weight oil. Our Coast Guard Search and Rescue diesels used 40 weight high detergent oil up in Ketchikan, but we had block heaters on them because we did not have time to warm them up.

[borderline 350]

Dear Misty 4,

Did you ask Mercruiser people how long the warranty period is for pleasure boat operation....or commercial operation?? 30 Days on the people using their boats for Charter Operation.....The local Rep can make a warranty decision and you will be stuck with it......As to using synthetics in marine/trolling applications, I do not see a benefit .Extending the change interval will be a detriment. Internal Condensation & long periods of sitting unused are your problems. No engine oil cooler on the majority of the I/O boats causes more problems with heavily loaded trolling boats. Change the oil often is better than all the paper warranties. 20W50 will work fine in most trolling boats, but Straight 30W will have slightly higher oil pressure (hot) at Idle! Approx 3 to 5# more. That's where you need it! The biggest positive change would be to use a specific additive at change time. Like Comp Cams Break-in additive and others that are based on the zinc compounds. NOT GM EOS...They took the Zinc out!. The EPA requested the removal of all zinc additives to protect cat. converters after 60K. This was done several years ago and we HAVE BEEN seeing roller lifter failures since then....etc. .....Respectfully Submitted....Jet Boat Bill......Jasper Engines honors their warranties ....after you send the engine back and they have time to inspect it.....Days turn into weeks & more while you sit on the dock. Take good care of your equipment and it will perform properly.

[Misty IV]

Dear Misty 4,

Did you ask Mercruiser people how long the warranty period is for pleasure boat operation....or commercial operation?? 30 Days on the people using their boats for Charter Operation.....The local Rep can make a warranty decision and you will be stuck with it......As to using synthetics in marine/trolling applications, I do not see a benefit .Extending the change interval will be a detriment. Internal Condensation & long periods of sitting unused are your problems. No engine oil cooler on the majority of the I/O boats causes more problems with heavily loaded trolling boats. Change the oil often is better than all the paper warranties. 20W50 will work fine in most trolling boats, but Straight 30W will have slightly higher oil pressure (hot) at Idle! Approx 3 to 5# more. That's where you need it! The biggest positive change would be to use a specific additive at change time. Like Comp Cams Break-in additive and others that are based on the zinc compounds. NOT GM EOS...They took the Zinc out!. The EPA requested the removal of all zinc additives to protect cat. converters after 60K. This was done several years ago and we HAVE BEEN seeing roller lifter failures since then....etc. .....Respectfully Submitted....Jet Boat Bill......Jasper Engines honors their warranties ....after you send the engine back and they have time to inspect it.....Days turn into weeks & more while you sit on the dock. Take good care of your equipment and it will perform properly.

Borderline, lots of great info there. Thanks. I am fairly sure my warranty has expired. The previous owner of the boat had to replace the engine and outdrive after failing to winterize the boat. I bought the boat with 10 hours on the new drivetrain 4 years ago. So, yeah, I'm probably out of that warranty claim liability now. After thinking about it, extending the OCI on the engine is probably not a good idea in a trolling application as you mentioned. I try to use my kicker as much as possible, but there are some days the main engine has to do all the work for 6-8 hours at a time. I know that is hard on a gas engine. Will running straight 30W have any effects on the engine for those days I just want to go for a long ride and the engine is at 3000rpm for an hour or so? Sorry for all the questions, but I just want to do this right. I am very an*l when it comes to maintenance on my boat (and truck) and want my investment to last a long time. Thanks again for all the input & help.

[muskybob]

Tag, I've been running straight 30 for 4 yrs now with no problems at all. Used mainly for trolling though with very little pleasure cruising. (over 1 hr)

[silverseeker]

My owner's manual calls for the MerCruiser spec 25W-40 oil. Ironically, Mercury Marine is the only 25W-40 out there. I'd like to run a synthetic oil in my engine, with the amount of hours it is running and trolling on the water. Other name brand oil manufacturers offer 20W-50 & 15W-40 in synthetic. I understand the differences in the numbers (been a motor head since I was 10 years old or so). In a marine application, will running a 15W make any difference than a 25W, other than the thickness of the oil when it is cold? I read somewhere in the MerCruiser manual that if an engine failure occurs due to a non-Mercury spec oil, the warranty will be voided. What does everyone else run in their MerCruiser engines these days? My engine is the 4.3L V-6.

Have a 2000 Sylvan offshore that I have run for 5 yr's with 15/40 diesel oil in my 4.3 190 hp. with no problem's and very comfortable venturing up to 70 mile's return trip offshore. HIH-Garry

[jimski2]

Ford Motor came up witha specification for 5W20 oil for its cars several years ago. The 5 weight synthetic oil quickly lubricated the engine slowing the wear process down. With the 210 degree operating temperature for fuel economy, regular oil would not last as 180 degrees is the maximum oil temperature for regular oil. The extra money for the synthetic oil was offset by the gas economy factor.

[JBoock]

Misty IV,

I have a 1995 Starcraft Islander 221V with a 4.3 Lx and I use Mobil one 15w50 synthetic oil. I found that it was easier to start in cold weather with the synthetic oil. I used the merc 25w-40 oil for one season and I think it is probably ok if you use your boat in May/June but if you use it in late March early April you will not have to crank so long before the oil will flow to kick on the fuel. The only bad thing about this oil is the price at $8.00 per quart.

Jay

[Splitshot115]

I run straight 30w in mine, carries better oil pressure when trolling over the 20w 50w. Very little use as a pleasure craft.

Splitshot115

[Knotlost]

I’m curious dose anyone know of a motor that has failed in the last 10 years due to oil? I say that because honestly I know of none that has failed due to oil, but lots of other reasons. It seems to me that better quality (not cheap no name) oil is of such good quality these days that none can be held responsible for motor failure.

Maybe im wrong but lots of what people say can not be proven, for example a spun bearing due to cooling failure not oil is sometimes tough to be honest about if your the guy who put the pump together wrong, just blame the oil (example). I run my motors way past what most will with synthetics and don’t have problems but I also know what’s going on with my motor and do have my oil tested by a lab once in a while so I don’t trust "magic" to know what’s good and what’s not. You can know exactly what your motors are doing and what in the motor is wearing with these tests. But even then you can’t put common sense aside.

[HPORT]

PK,

No, I have never in 25+ years of wrenching, pulled an engine apart to say oil caused a particular failure. Now most failures are in rotational assembly and its very easy to say that oil is the cause, its usually the secondary cause to the effect. Given the quality of today's fluids, it will be very hard to point a finger at the fluid as the initial failure point.

I rank the failures as follows;

#1 Lack of maintance

#2 wrong oil / filter or forgetting to put oil back in or tightening the draing plug

#3 my persoanal favorite, I wasn't abusing it... ( I removed black box data that had shown a customer had 14K RPM on the engine, with front wheel speed of 104MPH and rear wheel speed of 0 MPH, this car was FWD with a 6 speed...any guesses to what he ( 18 years old) may have been doing? )

John

[borderline 350]

Dear PK & JCRIDGE,

Go to Speed Talk and read in their pages about the tremendous number of camshaft & lifter failures in the past 7 years or so. The removal of zinc additives from conventional motor oils (by request of the EPA & done by all lube oil producers) IS THE MAJOR CAUSE OF CAMSHAFT & LIFTER FAILURE. I have seen several marine engine failures even with roller lifters! Took apart a 28K mile 1 ton van motor (5.7 SBC) with two scuffed roller lifters! Internal engine parts had no signs of sludge . Each one of the owners were convinced to add Zinc additive at oil change time in the applications w/o a cat. converter.

I use Mobil Syn. in my tow vehicle (has an eng. oil cooler)....but not in marine engines w/o engine oil coolers. ...As age and time on the marine engines increases, more failures occur and the repair costs are going thru the roof!!! The long hours of trolling is very hard on the valve train. CHANGE THE OIL @ regular intervals (60 hours) and you get a long engine life unless the unleaded gasoline & ethanol eat your valves and seats first!!

.......Sincerely,

.........Jet Boat Bill

[Knotlost]

I went to speed talk and didn't find any pages of camshaft and lifter failures? Can you give locations? In the cases that you mentioned, how would you know if it was the oil? It certainly could have been other causes, and it would seem that oil would have a greater impact on the journal bearing than camshaft and lifters? I’m not an expert and I'm not saying your wrong but pointing the finger at oil is just to simplistic in my opinion, especially when you see shear test, load test and all the other test they do in order to compare today’s oils of those used 10 years ago, they all surpass them buy a substantial amount, and that can not be dismissed, its science that’s repeatable. I would sooner question the enginering design of some of the motors today, when thin parts, small surfaces, rushed heat treating process, junk case hardend cast, where forged used to be the standard, and that can cause failures you can not detect with the naked eye, but would at first appear to be an oil problem. How about parts made by the highest bidder in China? You need a brinell tester and a microscope with a trained eye to detect these failings.

I belive this because there are some well built motors that run great and run for a long long time with zerro problems, regardless of the oil, and if there was poision in the soup everyone would be sick. These motors are high quality though out but again manufactures today change methods and supplyers almost monthly and you can not rely on the fact that last year they made a good motor that this year they will. AT least this is my opinion.

[HPORT]

Both points noted,

Engine manufactures have not kept pace with EPA regulations on petroleum standards. Remember leaded fuel and the issues with burnt valves when the the EPA removed the lead additives from the fuel supply? The industry replied with hardened seats and new materials to combat the unleaded fuel effects on the valve train.

Zinc reduction is no doubt similar, and there will be issues just the same. Zinc was one of the components in our cam lube for years. Until we get to the point of a zero impact synthetic, we are going see the industry ebb and flow with each new regulation.

The cam failure in my opinion, is not the oil itself, but the application of the oil on a component that was not specifically designed to run with that specific oil rating. GM back in the early 80's couldn't keep a camshaft from wearing on V8's, they finally got on board with the other manuafactures and have a fairly good track record since. The engineers / manufactures know their business as well as anyone, cost is the main driver. Acceptable failure rate would be something that is on their table, no one is 100%, but some are real close.

John

[borderline 350]

Dear PK.... Post a message and use the history search (on Speed Talk) for Zinc additives. There are several camshaft & engine Guru's on there. Including Dart, Iskenderian, Comp Cams and many excellent people directly involved in the aftermarket business. If you do the homework and read carefully, the zinc problem will be very evident.

....Dear JCR, Yes we were told & sold by GM that it was a soft cam and lifter problem.....only their is more to the story. A LOT MORE! When the aftermarket & NASCAR people did the inspection on lifter bore angles....they found that the angles were off several degrees on some lifter bores in SBC production engines (GM wouldn't admit this because then they would have to replace short blocks$$$$$). And so special tooling & lifter bore bushings were developed by the engine guru's. NASCAR and other racing demanded better quality parts then GM could produce....so the aftermarket people now have the majority of all the replacement & new business. And GM has taken all their engine manufacturing (SBC & BBC) to Mexico with parts sourced from all over the world!!!This happened several years ago. More headaches....Mexico SBC parts are not the same quality as US Produced parts (Tonawanda/Flint etc) Read some of the posts on Speed Talk about variations in head castings, intake manifolds etc. from Hencho in Mexico parts. In closing....Change the oil often and keep your equipment in good condition and hope that it gets you out and back......Repectfully submitted....Jet Boat Bill

[HPORT]

Bill,

Yeah, we had allot of reboring and truing to prep a SBC for anything more then a grocery getter. It's a shame the 020 and 030 SBC blocks are gone, and those who have them will never give them up. The early seventies produced some of the best block castings ever made. The mid sixties produced the best SBC heads, it's all been down hill since. Know anyone looking for 462 heads?

I agree with you on today's engines, regular PM is the best method to long life, but with the improved oils today customers can abuse the schedule more then ever. The last good engines I remember GM making where from the Canada plant.

John