Gasoline engine oils

[After Taxes]

As gas Mercruiser owners, we know the factory recommended lubricant is the Mercury Quicksilver 25W40 conventional oil. I am using it now in my Merc GM 6.2 blocks. In my area, marinas sell this brand for around $36.00 for a four-litre jug.

There's so much written about engine oils - some confusing.

I've read that the Shell Rotella Triple Protection 15W40 is a good alternative. I saw this brand at my local auto PartSource store on sale for $25.00, for 5.5 liters, regular price of about $28.95. This oil is made for the Diesel engine market, but I believe some gas boaters use it. Do you? If so, do you like and recommend it?

Some use straight 30 weight oil.

So what's your engine oil experiences, likes and/ or dislikes?

If you have the marina do your oil changes, do you even know what they put into your engines?

If you are a do-it-yourselfer (I am) then you get to choose your oils. What's your preference?

Feel free to go all out in this topic. Perhaps you want to write about brands, blends, or conventional versus synthetics. I used Volvo synthetic on my last Volvo GM block boat.

Cheers all

Steve

[Midnight Sun]

Ran my last 3 gassers on Rotella T 15w-40, never an issue. All 3 are still running today with the 7.4L at well over 2000hrs. Oddly enough I will continue to use the Rosella t 15w 40 in my Volvo diesels.

[waybomb]

I also am a Rotella T guy. Both the carver and the cougar get 15-40

The drag boat gets 50w.

The cougar and drag boat also get 2 pints of the old gm eos engine oil supplement. I use the original stuff that has good of zddp in it. I have a couple of hundred pints to go before I run out

Lots of debate on the use of adding zddp. All I know is I have been adding eos since my first engine build-up, bought a1968 gto the day I turned 16 and 3 months later had the engine apart.

I have grenaded quite a few drag engines but none of those cranks on the ground experiences or rods through block episodes are oil related.

My cars all get Mobil 1 5-30. The last car I sold had 357000 on the click and not burning oil. FSS dictated my oil changes and usually it would prompt for an oil change at about 18000 miles. So in all those miles, maybe 19 oil changes?

Point is, I have to say I am not so sure if my oil practices are correct, but they seem to work for me.

Carver gets oil change when I put it away for the winter.

Cougar gets 12 gallons every 20 hours or so. 16 quart pans. Times 3.

By the way, Walmart had the best oil prices always. . 5 quart jug of Mobil one gold cap is only 25 bucks or so.

[DanM]

I have been and currently use in my Mobil 1, 15W50 in the Volvo Penta engines, 10W30 in the generator, and Redline Synthetic in the ZF 80A transmissions. Synthetic is my choice, not a mandate by any manufacturer although Mercruiser and Volvo Penta are starting to advocate it's use. Some of the marine transmission shops are recommending it due to synthetic's rapid heat dispersion.

[mjk1040]

In researching oils when I replaced my 5.7's long blocks in our 1986 Mariner, the engine rebuilders strongly suggested using engine oil with zinc in it or making sure a zinc additive was used. They listed oil brands and Rotella T along with several racing oils were listed. Racing oils will run you $8>$10 a quart, were Rotella T's can be purchased at Tractor Supply on sale for about $3 a quart. It's my understanding that the zinc helps the oil stick to all the metal parts it lubricates, thus you never have a dry fire situation. Another boater next to us was changing his oils prior to my engine replacements and he was using Rotella T and I questioned him on it and he stated that he used Rotella T in everything he owned, cars, trucks, motorhome and his boats. He said I have never had an engine issue. So to this day all I use is Rotella T. As far as what viscosity, I was never a found lover of multi wright oils, so I go with the straight weight oil and if my memory serves me right, the 7.4L Crusaders call for 40W and that's what they get. Bottom line is zinc weather it's in the oil or you add Lucas zinc additive. Mike

[waybomb]

Shell did reduce some zinc a few years ago.

[After Taxes]

When running about 50 hours, or much less than 100 hours per season, and doing one oil and filter change, how important do you feel it is to change at fall layup, versus the spring or summer? I've read opinions saying dirty oil shouldn't be left in engines over winter, but on low use engines, is that really such an issue?

[Viper]

Here is one of Merc's top techs and instructor's take; As soon as dino oil leaves the ground and is exposed to air, its protection properties begin to degrade. By the time it gets to the end user, we have about a 3 month window of optimal protection quality. This is why you always hear the recommendation to replace dino oil after so many miles/hours or 90 days which ever comes first.

This 90 day finish line seems to be enough of a concern that there has apparently been talk in Merc's inner circle for years about sticking to their guns on warranty claims for catastrophic failures if they find the oil in the failed engine is more than 3 months old and no other reasonable cause for the failure can be determined. OEMs are recommending synthetic oils now not only because of their superior protection qualities but also because of their extended shelf life. Haven't heard yet though of a claim being denied due to the age of the oil in a failed unit. In fact, I have yet to see a failure in a recreational application due to the age of the oil (not hours of use) or the type/grade/make of oil being used.

There are a couple of schools of thought when it comes to oil changes before or after winter layup. Combustion, whether for only one hour or 100 hours produces caustic by-products that end up in your oil and in contact with vital surfaces in an engine. These acids can etch the surfaces of some vital components and shorten life. For this reason, I prefer oil changes prior to winter layup so that for the most part internal surfaces are coated with a fresh layer of clean oil rather than an extended period in a caustic soup. This goes for generators too by the way which are probably neglected the most because "I hardly used it" (engine killer!)

Having said all this, it never ceases to amaze me the amount of chatter on forums about oils and whether they should have this or that additive as if it's going to make a big difference. As mentioned earlier, especially in a marine recreational application, I have yet to see or hear of a catastrophic failure due to oil type/make/grade, lack of an additive, or whether it was changed in Fall or Spring. I've torn down quite a few and no meaningful red flags have ever surfaced as the oil being suspect or the lack of additives. In a marine application, the vessel will probably be scrapped before the effects of oil deficiencies are the cause of a serious failure unless there is gross maintenance negligence but that's not what we're discussing here. It's more likely that a major failure will happen due to bad exhaust manifolds, poor fuel quality from lack of use, lack of fuel and ignition systems maintenance, how vessel is used, etc. etc. These areas is where we should be focused on more as they are historically the causes of failures, not oil.

Rotella T, I put that s**t in everything. Don't tell Merc, CAT or Volvo I said that! There are some diehard customers that want the more expensive OEM stuff and that's fine, I'll take their money but it's not necessary. Politics come into play as well here though, dealers have to carry the product and that's okay too as they are trusted brands and all highly recommended.

And that's my rant for the day

[After Taxes]

Many thanks, Capt. Bob.

[mjk1040]

I agree with all Viper says, and I am a firm believer in the haul out oil change, and using a good filter. Mike