Seasonal Engine Oil Change

[tc123]

This past boating season I only logged about 5 hours of running time on my Mercruiser 470 due to repairs and weather issues that kept me off the water most of the season. Will I be doing any harm to the engine by not changing the engine oil before winter storage and run with this current oil next season as well? Normally I always drain and re-fill with new oil before winter storage. I use Mercruiser conventional oil.

 

[JASinIL2006]

After five hours, it is still almost brand new oil. It certainly wouldn't have broken down at all and I can't imagine it would have picked up enough contaminants to cause any problems. I know plenty of people who own classic cars that are run for a few days and then are garaged for months, and they certainly don't change the oil that frequently.

Unless the oil before the current change was REALLY dirty, I'd probably leave it.

 

[Starcraft5834]

I agree. there's no need to change it. do drain and replace your drive gear oil though...

 

[tc123]

Thanks for the info. Just wanted to get a few other opinions. I will drain/replace the gear oil just in case of water contamination.

 

[j cat]

Thanks for the info. Just wanted to get a few other opinions. I will drain/replace the gear oil just in case of water contamination.

I have a 1979 470 in a 20ft wellcraft. .. in 2010 I used my boat. winterized it with leaving the oil used that year in it. this year 2015 I used the boat . sat 5 yrs . fuel tanks 2010 drained completely. added new fuel and it started up good . got to operating temp then drained out the 5 yr old engine oil. used 15-40 wt with about 8OZ of the zinc oil additive. engine ran great all season ...used no oil..plugs looked new when I added oil to the cylinders this week .

on the drive ..I always take off that top cap on my MR alpha drive.. if I see condensation ,then the drive has a leak... I also use a pressure gauge and put 7 PSI of air in the drive to check for leaks .. if it holds pressure for a day then no leak. I keep the drive in my house not on the boat in winter.. drive is 1979 still in good shape.

exposing the drive to extreme cold temps then hot in summer this can get those seals to breakdown and then the leaks. also water will get to the drive in places like the lower shift shaft seal and damage it. last time i took my drive apart was in 2005. I had 2 leaks.also water pump impeller distorted.

I use light wt engine oil to flush out the drive if with water.then after repairs pressure test. I just checked the upper gears in the drive and the metal is perfect.

owned this since oct 1986. have had good luck with it ..

 

[philipp10]

I would NOT change it. That oil is practically new. As far as the drive, what I do is pull the lower plug, drain an ounce and as long as no water comes out, I leave it be. I put about 20 hours a year on my boat and for this year, I will skip the oil and gear lube change. I will for sure change it after next season though.