Synthetic or Non Synthetic Motor Oil

[Ccoe1]

I have a 5.0L merc carb on my '99 210 sundeck, purchased this year. My manual says not to use synthetic oil, but everything that I have read on here and else where says synthetic is the way to go. Looking for any input as I am going to be winterizing soon. Past changes were done by the marina with mercruiser 25w 40 oil. I only ask because I am a big fan on synthetic oil in my truck.

 

[grayzone]

I use Mercruiser OEM Fully Synthetic 20W-40 Engine Oil

 

[blaster]

Use synthetic if you feel like spending more money. Synthetic oil is required on the new ect engines to keep the emission controls from getting messed up. On your setup it probably won't give you more run time. Now if you change the oil every 3 years, synthetic oil may hold up better. If you do the maintenance on schedule, then synthetic is just more money and feel good points.

 

[Lazy Daze]

Your manual was written well before Merc approved (or sold) any synthetics for marine use (boats should use an FC-W rated oil). The manuals now include full synthetic as the #1 recommendation. BUT, you can keep using the 25-40 dino oil without any worries, as well. Your call.

 

[Sidebar]

I have a 99' 5.7 Merc. Any recommendations on how often to change the oil? I just bought a 240 a couple months ago. I have had outboards but this is my first I/O.

 

[Escapade]

Every 100 hours or at the end of each season.

 

[Sidebar]

Thanks! for the info Escapade.

 

[griff4]

Here in Florida it's straight SAE40 year around and not synthetic. Griff4

 

[Got2Cuff]

I have a 5.0L merc carb on my '99 210 sundeck, purchased this year. My manual says not to use synthetic oil, but everything that I have read on here and else where says synthetic is the way to go. Looking for any input as I am going to be winterizing soon. Past changes were done by the marina with mercruiser 25w 40 oil. I only ask because I am a big fan on synthetic oil in my truck.

I use synthetic Mobil 1 in all of my vehicles. I used to use it on my single engine 1998 Mercruiser 5.0 I/O. However, I now have a twin engine set up, boat in New Jersey less than 100hrs use per season. I change at end of season using Shell Rotella 15-40 on my twin 5.7 Mercruiser MPI Horizon 300hp motors. Pick it up @ Walmart around $12 a gallon.

 

[Ccoe1]

I'm thinking about using the full syn shell rotella 25w 40