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drdoyal
10-28-2007, 11:12 AM
The Indmar manual from 1994 to 2002 recommends Pennzoil Marine
15W-40 Marine Oil API Service SJ/CG4 or equivalent. This has been very difficult for me to find. In years past, I have used a Castrol GTX diesel oil that meets these specifications. I've recently found the Mastercraft owner's manual for my 1997 ProStar 205 (LT-1 engine) and it recommends using SAE 20-50 Racing Oil with API service SG, SF/CD. I've done a little research on the API ratings (www.api.org). The S ratings are for gasoline engines and the C ratings are for diesel engines. The most current rating of SM meets and exceeds all previous ratings (SL, SJ, SH, SG, SF, etc). The current diesel rating of CJ-4 meets and exceeds previous ratings (CI-4, CH-4, CG-4, CF-2, CF. CE, CD-II. CD, etc) I'm thinking that as long as an oil is rated at SJ/CG4 or newer it be in compliance with both manuals. However, I'm confused about whether I should use a 20-50 (MC manual recommendation) or 15W-40 (Indmar recommendation). And do I need to find an oil that is branded or marketed as a "Marine" oil or "Racing" oil? Any advice would be greatly appreciated!

TX.X-30 fan
10-28-2007, 11:18 AM
I highly recommend using oil!!!! :rolleyes:

bigmac
10-28-2007, 11:50 AM
Indmar currently recommends CI-4/SL, which as you say encompasses all previous API service classifications. The current classification is CJ-4/SM or you could use CJ-4 Plus, both of which also meet or exceed previous. I would use 15W40 as Indmar recommends in their pre-2003 owner's manual. IMHO, their recommendations supersede MasterCraft's, since MasterCraft's owner's manuals are based on Indmar's recommendations at the time. Indmar has changed its oil recommendations since your manual was printed.

brat
10-28-2007, 12:13 PM
It's not that big of a deal, go with a high quality oil of either viscosity. I personally use 20w50 Mobil One.

yippikaiyay
10-28-2007, 06:15 PM
I also made some inquires last year with my 97' 205, and received various viewpoints. I decided to go with a high quality 15W40.

bigmac
10-28-2007, 06:40 PM
And do I need to find an oil that is branded or marketed as a "Marine" oil or "Racing" oil? Any advice would be greatly appreciated!

No, most likely the CJ-4/SM or CJ-4 Plus oil you find will be labeled "diesel". The same oil may be labeled "marine", but that's just marketing. Same for so-called "racing" oil.

André
10-28-2007, 06:48 PM
No, most likely the CJ-4/SM or CJ-4 Plus oil you find will be labeled "diesel". The same oil may be labeled "marine", but that's just marketing. Same for so-called "racing" oil.
You never get tired of oil questions Big Mac ?;)

Chief
10-28-2007, 07:05 PM
You never get tired of oil questions Big Mac ?;)

Mac has answered so many times he just cuts and paste now. A well of knowledge all all worldly things.

bigmac
10-28-2007, 07:06 PM
You never get tired of oil questions Big Mac ?;) They're mostly the same 5 or 6 questions...:D

rstitson
10-30-2007, 08:21 PM
I settled on Ames 15-40 synthetic. Seems to hold up better than Penzoil; The oil is not as black or broken down after the 50... I use the standard 15-40 Penzoil in the v-drive every 100 hours. Looks new when I pump it out.

kjohnson
10-31-2007, 10:34 AM
I use Mobil1 full synthetic 15W50 in a 1991 PS 190. At $7/quart it better be d..n good.

mitch
10-31-2007, 10:45 AM
I can find Pennzoil 15W-40 long life Gold locally, and that's what I use in a 2000 MC. I also only use Wix filters. I'm certainly no expert.....but do play one on the internet

---Tank is topped off and stabiled and changing my oil~filter~fogging ~draining today. Unfortunantly getting ready to put her away- sad day:cry:

BrianM
10-31-2007, 10:49 AM
I use Mobil1 full synthetic 15W50 in a 1991 PS 190. At $7/quart it better be d..n good.
That is not the reccomended weight from Indmar nor does it meet the CG-4 rating. Also as per Indmar even if you use a synthetic the change intervals must stay at 50 hours. So what exactly are you getting for $7 a quart? As BigMac has said many times with modern dino oil as good as it is the only advantage to synthetic is an extend change interval. Indmar took that away so your advantage to synthetic is zip, zero, nada. I'll stick with the Rotella T 15w40 that meets or exceeds all Indmar reccomendations and costs me $12 a gallon at the local NAPA. Total cost of oil change including NAPA Gold (WIX) filter $22. That synthetic you are using is a waste of $$. :twocents::twocents:

kjohnson
10-31-2007, 10:55 AM
The 15W50 was recommended either in the MC manual or somewhere else, I don't remember. The synthetic gives me a secure feeling.

BrianM
10-31-2007, 10:57 AM
The 15W50 was recommended either in the MC manual or somewhere else, I don't remember. The synthetic gives me a secure feeling.

If synthetic gives you a sense of feeling fine but use a synthetic that meets the proper ratings.

kjohnson
10-31-2007, 10:58 AM
It does meet the proper ratings!

BrianM
10-31-2007, 11:01 AM
It does meet the proper ratings! Actually it does not. From the Mobile 1 website (http://www.mobiloil.com/USA-English/MotorOil/Oils/Mobil_1_15W-50_.aspx)
API SM/SL
Requirements for Diesel Powered Vehicles where an API CF or API CD is recommendedCG-4 is a higher rating than CF or CD. It does meet the API rating however.=

JLeuck64
10-31-2007, 12:26 PM
Whoa now fellas!

It's just oil... right? Yea, some is engineered better than others that's for sure.

Oh, for what it's worth. Synthetics do reduce friction, which in turn increases HP. Sure it's not much but it is measurable on the Dyno. That increase should help reduce fuel consumption???

By the way I don't use Synthetics...

gogo
10-31-2007, 12:54 PM
Just a point that has not been mentioned. During my factory tour i enquired about the oil issue and what was mentioned was the need for the added detergent agents found in there recomended oils.
I agree with the thought of "extra" protection aforded when a synthetic is used. It should be noted that all auto manufactures are looking at increased intervals for oil changes based on synthetic usage. Hope this helps.:purplaugh

phecksel
10-31-2007, 09:01 PM
Neither MC nor Indmar have the resources to test their engines and the impact from different oils. It took forever for the auto companies to jump in the synthetic band wagon. My own experience and others have led me to only use synthetic oils. Why would a cool running engine like our IB's need 40 wt oil? New auto engines, which run considerably hotter only need 20 or 30 wt. Diesel engines have their own special needs, which don't even come close to the conditions of our engines.

bigmac
10-31-2007, 09:29 PM
Neither MC nor Indmar have the resources to test their engines and the impact from different oils. It took forever for the auto companies to jump in the synthetic band wagon. My own experience and others have led me to only use synthetic oils. Why would a cool running engine like our IB's need 40 wt oil? New auto engines, which run considerably hotter only need 20 or 30 wt. Diesel engines have their own special needs, which don't even come close to the conditions of our engines.


To clarify, auto manufacturers have specified certain oil requirements that oils must meet to be OK to use in their engines. These can be either mineral oil, or synthetic. GM6094M, for example, now allows the use of synthetic oil, among other oils, in their vehicles. Not quite "jumping on the synthetic bandwagon". And note that the drain intervals are the same as for mineral-based oils.

Don't get me wrong...nothing wrong with the concept of synthetic engine oil...I use it myself in my truck (only in the winter - for cold starting) as well as my lawn mowers,motorcycles (air cooled, high heat). Waste of money otherwise in an automobile IMHO. Likewise boats. However, those who do fall for the marketing can be assured that good quality synthetics won't hurt your engines. There are some bad quality synthetics out there, which is why GM put out it's own standards rather than rely on just the basic API service specs as the determiner of appropriate quality.

Boat engines get a lot of wear due to the lack of a variable transmission. Lugging on the low end, close to redline on the top - a boat never really gets to run consistently at the sweet spot of its torque curve. Pressure and wear characteristics of marine engine use mandates oil that can stand up.

kjohnson
11-01-2007, 09:20 AM
For the record my manual recommends SAE 30 wt meeting API. But I am not going to argue about this anymore. It is not worth it.

bigmac
11-01-2007, 09:25 AM
For the record my manual recommends SAE 30 wt meeting API. But I am not going to argue about this anymore. It is not worth it.


Indmar has now recommended CI-4/SL or equiv API for all of their engines retroactively, regardless of what the original owner's manual says, but IIUC, your boat has a non-Indmar engine.

phecksel
11-01-2007, 11:39 AM
Some auto engines now require synthetic.

Indmar had a program of lifetime warranty if you ran mobile 1.

I borrowed mom's old duster, when my car sold too quickly and my new one was delayed. It always had a startup and low idle rod knock. Dad ran nothing but mobile 1 in that car, with way over extended oil changes. Anyway, while I had the car, the starter went out (130k miles) and i had them check the oil pressure...apparently the check valve had been missing from day one. that engine was as still running strong at 170k when they sold the car. Couple of friends that race and tear down engines, have said they can always tell a car that has run synthethic, it always looks cleaner then one that doesn't.

Diesel engines get a lot more stuff built up in their oil, more then our auto gas engines will ever see. Looser tolerances, higher combustion pressures, far far worse.

An aviation magazine years ago did an article trying to prove that running lean of peak would cause engines to self destruct. Part of their calculation involved cylinder pressure with heavy load and low RPM. What I was surprised at, was the old wives tale about cylinder pressure was not correct. BTW, the article made a point that LOP operation was actually better for the engines, LOL. they killed two wives tale while trying to prove one right :)

What's funny, in the quest for HP, mfg's are specifying 20wt max. These engines run far far hotter then our engines will ever see! Indmar is not big enough to truly test and specify oil. I'd be willing to bet they were sitting in a room looking to cut warranty expenses and a genius offered that we should get the highest rated oil available...hence, we're stuck with far more then we'd even need in our auto engines. there is nothing wrong with the choice, other then it's over specified.