View Full Version : Mobil 1 Synthetic Oil

08-05-2004, 08:49 AM
The previous owner of my 97 PS190 LT1 used only Mobil 1 Synthetic Oil. Is there a specific grade of Mobil 1 synthetic designed for Marine engines? Most of the retail stores carry 5W-30 and 10W-30. What weight should I be using? Thank you.

08-05-2004, 09:32 AM
As a Mobil distributor I can tell you that the previous owner made a wise decision on oil but a poor decision on vicosity. Marine engines run much warmer and at higher RPM's than car engines. Therefore you need an oil with a higher vicosity. My recommendation is Mobil 1 15W-50. This will provide excellent protection especially on those hot summer days when you are out skiing or boating all afternoon. If you go to Autozone or Pep Boys, or most other auto parts stores, you should find Mobil 1 oil filters. They pick up 95% more dirt and particulates than standard oil filters. My Dad's '84 American Skier has been running on Mobil 1 15W-50 for 20 years now and it still runs like new. It even provided excellent protection when our impellars when out twice and overheated the engine. No damage was done. You can't go wrong with Mobil 1. :)

08-05-2004, 09:38 AM
The owenrs manual on my 1996 LT1 called for 10w50. I used used 15w50 while I had it.

08-05-2004, 09:38 AM
The owners manual on my 1996 LT1 called for 10w50. I used used 15w50 while I had it.

08-05-2004, 09:56 AM
Not to disrespect that last comment, but Mobil 1 does not make a 10W-40 synthetic. They did however just come out with a new Truck/SUV formula 5W-40. This might be a better alternative to the 10W-40 if your owners manual requests that. A lesson on oil: Must peopel assume that the "W" in the formula means "Weight." Not true! The "W" stands for "Winter." Meaning that the first number represents cold temp. protection while the second number represents hot temp. protection. Seeing that you live in Florida, it is unlikely that you will be skiing or boating in 40 degree temps. Therefore you need an oil with hot temp. protection. The higher the second number the greater the protection against warm temps. Again, I would recommend the 15W-50. I know the owners manual on my 2001 Maristar recommends 20W-40, but Mobil does not make that in synthetic formula.

east tx skier
08-05-2004, 10:17 AM
I'm, by no means, an expert on oil. Furthermore, I have a different engine on my boat than was referenced in the question.

That being said, I called Indmar at the begining of the summer. For my boat, they recommend 15W40. They recommended Penzoil, but that may just be who they have a deal with these days. My manual recommends Mobil 1 SAE30. As I understand it, either MC or Indmar used to have an arrangement with Mobil 1, and use of Mobil 1 had something to do with the engine warranty. Just a little trivia. I've seen nothing to believe anything but that Mobil 1 is a fine brand.

08-05-2004, 10:40 AM
Smitty, I am not sure what grade of Mobil 1 synthetic the previous customer used. That is why I asked the question. Are the 20w-40 and 50 grades you recommend synthetic? :)

Sorry Smitty, I meant to say 15W-50!

08-05-2004, 11:36 AM
Smitty, thanks for the good info. However, you guys are confusing the heck out of me. You keep referring to numbers that scubat didn't use, so I'm not sure what's going on? (hey, where's the little scratchy-head guy?)

08-05-2004, 11:55 AM
Smitty I have question about mobil one also. This is just a question so don't take it wrong. I change my oil every 50 hours or less for that matter. I use Pennzoil 20w-50 when I change it. Since I change it so often would I get the benefit of using Mobil 1 15w-50. I've heard nothing but good stuff about Mobil 1, period. I just don't know if I need it since I change my oil so often.

On a side note. I have a 04 Ford Powerstroke have you heard of any issues with people using Mobil 1. If not what weight woud you recommend and how often would you change it? I currentlly use the new Delo 15w-40 oil and change my oil every 3k.


08-05-2004, 12:08 PM
Just my experience. I have always used Mobil on both my cars, a Jeep Cherokee and a BMW 3 series. About 2 years ago I started using synthetic on the Jeep and within about 6 months, it developed a nasty leak from the rear main bearing. I went back to standard and the leak slowed almost to a stop. I then read on a BMW forum that some of the owners experienced similar seeping with synthetics. I'm still using Mobil, but standard.

Tom Wortham
08-05-2004, 12:21 PM
Is it true, "once you go Synthetic you don't go back?" (With exception to Knoxes situation). I have always run non-synthetic in all my vehicals and my MC. No problems. Cheers. :cool:

08-05-2004, 02:15 PM

For you Powerstroke, you will want to you an oil that meets the requirements of your diesel. I know that some of the newer grades of Mobil 1 have meet some of the diesel requirements, but certainly not all grades or requirments. I would recommend Mobil Delvac 1, a full synthetic diesel grade oil. http://store.avlube.com/fonfacsizcol.html That is what I use in my VW TDI. I would also recommend an oil analysis or two, with the large capacity you might be wasting lots of good oil every 3k.

I use Mobil 1 15W-50 in the MC.

99 MasterCraft SportStar CB PrefectPass…
00 Jetta TDI Silver GLS 5 spd…
94 Jeep ZJ Red SE 5spd…

08-05-2004, 03:22 PM
I swear by Synth oil and have been running it in my '83 powerslot forever. Mobil 1 is good stuff, but I run Amsoil everything from oil to gear lube to ATF in my cars, the M/C, my Edgewater (twin 200 4 strokes) even my lawnmower. Life is too short to run cheap oil...


08-05-2004, 03:34 PM
You can't go wrong with Synth Oil. Mobile 1 is good stuff and I concur with the filter change. Was told Synth Oil tends tends to carry particulates better than its counter part hence the obvious need for a better filter. I have been running Amsoil Synth 0-50w in my '83 Powerslot forever and she's purring away... but I too was told to switch oil filters I change the filter every 25 hours, and the oil every 100 hours. I run the amsoil filters. From my positive experiences, too many to mention, with Synth Oil (engine oil, ATF, grease, gear oil, lower unit oil, 2 stroke oil) I run it in everything, the M/C, the Edgewater (twin 200 Yama's 4 stroke), all the cars even the lawnmower and weedeaters... Never had any oil related issues, just maintenance... When I sold my last truck I had 775K miles... nope that's not a typo... 9 years old... didn't owe me a dime...

Life is too short to run cheap oil... pay now or pay later...

H2O-ski dude
08-05-2004, 04:01 PM
I have switched over to Mobil 1 15w50 synthetic last year on my '97-PS190, and you could noticeably hear that the engine was quieter. I also changed to a full synthetic for the trans. as well. This made a huge difference. It shifts smoother, runs quieter, and I highly recommend it.
I change the engine oil every 50hrs., transmission oil at the beginning of every year, wax it 3-4 times a season, wash it every other weekend, and wipe it down everytime it comes out of the water.

Most people think my boat is brand new. I am a little annal about its upkeep. It's a 97 with not one scratch on it, and we ski almost everyday.

Hope this helps.

08-05-2004, 05:17 PM
I believe that Mastercraft endorsed Mobil 1 synthetic as its factory fill during the '90's and specified it as the recommended oil change to cover the warranty. Today Indmar has endorsed Penzoil as its oil of choice. This comes straight from the Indmar website:

"Indmar recommends (and uses at our factory) Pennzoil Marine 15W40 Motor Oil. If Pennzoil 15W40 Marine Oil is not available in your area, we suggest using 20W40 or 20W50 oil meeting the API specification of SJ/CG4 or better. Synthetic oil that meets our requirement of 15W40and API rating of SJ/CJ4 is acceptable to use after 100 hours or operation with the recommended (not synthetic) oil. The use of synthetic oil does not alter the requirement for oil changes at 50-hour intervals. Older operator’s manuals, and other publications that are not regularly updated will not be revised to show this latest engine oil recommendation. Current operator’s manuals, and other service publications that receive regular updates will receive this revised recommendation the next time they are updated "

You can see, 20W-50 is a recommended oil meeting engine specs. As for changing oil; I would suggest that you wait until your next oil change to add Mobil 1. Most synthetics brands will not mix well and coventional and synthetic do not mix at all. So do not add synthetic to your engine if you have conventional already in the engine. Wait until your oil change.

As for the Ford Powerstroke, Mobil does make a synthetic for diesels. It is marketed as Mobil 1 Delvac. As for the grade you should use, you can check www.Mobil1.com and they have a search engine you can use to see what is recommended for your vehicle. ;)

08-05-2004, 06:03 PM
Oops :( I goofed My 1996 LT1 called for 20w 50. I used Mobil One 15w 50 still have on bottle left. My 2003 LQ9 calls for 15w 40. I spoke to indmar last week and they did not recommend synthetic oils. They said to use a normal 15w 40. They said if there was ever a problem with the engine it could not be honed(??) or something like that, after using synthetic. I have no idea. Just what I was told.

08-05-2004, 08:15 PM
Yes synthetics are great, Mobil 1, Amsoil, Redline - the latter two especially if you race anything - you change it enough you don't need the added detergents, which cause a lot of the carbon build up in engines. However one thing needs to be mentioned - if you have an engine your rebuilding, DO NOT start it out on synthetic when finished with your rebuild, as the rings will not seat properly in your newly honed bores. We break in several Porsche motors using 30w non-detergent dino oil for the first 150 miles(10hrs), then switch to a multi-viscosity dino oil for another 200 miles(10-15hrs), change to whatever you want and go. We did a 380rwhp 944 turbo the other day. Vacuum started at 15.5 in hg when the car was warm after we started it for the first time. After 328 miles(broken in as above) the vacuum today was down to 19.5-20 in hg at warm idle, all 4 cylinders were less than 1% leakdown. Just my .02
I personally use Mobil 1 15w/50 in my 94 Prostar 190. I have a 95 Jeep Grand Cherokee that Jeep had to put a new engine in due to a rod failure. The engine, Mobil 1 10w/30, at 61k was virtually like brand new when they took it apart, well except for #1 cylinder. :D

east tx skier
08-06-2004, 10:23 AM
Bret, I used to have an 84 Jeep Grand Wagoneer that would change its own oil. I'd put it in the top, and it'd drop it out the bottom. :D

08-06-2004, 02:10 PM
I plan to use the recommended Penzoil 15W-40 Marine oil in the boat ($1.75 per qt at Walmart).

I use Mobil 1 in the NSX because it revs to 8000 rpm, and uses the oil to hydraulically power the VTEC valvetrain.

I use Mobil 1 in the BMW because it has unusually long service intervals (10-12k miles between oil changes), although I change it between service intervals (still over 5k miles). BMW also "requires" synthentic oil, and Mobil 1 is cheaper than their Castrol synthetic. It also holds 7 quarts!

I used Mobil 1 in the '91 300ZX Twin Turbo to prevent "oil coking" in the turbo shaft bearings.

I use Mobil 1 where I think I need a synthetic, otherwise I stick with a namebrand dino oil. Redline and others would be good, but are much more expensive than the convenience of buying a 5 qt jug at Walmart for $20.

If you don't have a specific need, its my opinion that using synthetic oil is a waste of money.

I usually avoid oil discussions because everyone has a different opinion, but this is my .02

08-06-2004, 02:29 PM
Bill, got a pic of the NSX? Maybe this should be in off topic but it is oil related ;) Here is my street car, 87, 326rwhp @15psi and the track car, should be 370+ at 2422 lbs after tuning - depends on boost.
Mobil 1 15w50


Amsoil 20w/50 once it hits the track.

08-06-2004, 02:44 PM
Here ya go. Both use Mobil 1

08-06-2004, 06:23 PM
I wanna see a pic of the NSX pulling the 209!!!