Go Back  Offshoreonly.com > Technical > General Q & A
Recommended oil for my 7.4 > Recommended oil for my 7.4
Like Tree7Likes

Recommended oil for my 7.4

Reply

Old 05-28-2014, 03:42 PM
  #1
Registered
Thread Starter
 
Join Date: May 2010
Posts: 11
Default Recommended oil for my 7.4

Hi I live in Michigan and am getting ready to fire up my old 1989 chaparral 7.4 Mercruiser. The boat has been sitting for 6+ years. I was gong to run a cheaper oil just for the start up then put in some Mobil 1. Any suggestions on what weight to use? I was thinking 20w-50
kwtv38 is offline  
Reply With Quote
Old 05-28-2014, 04:23 PM
  #2
Registered
 
Join Date: Apr 2013
Location: Lagrange ky
My Boat: 88 pachanga 22
Posts: 242
Default

For a cheap oil i run delo 15 40 it has all the good stuff in it for flat tappet cams. Alot of over the road guys run it.
beaver 3 is offline  
Reply With Quote
Old 05-28-2014, 04:27 PM
  #3
Pirate of the Chesapeake
Gold Member
iTrader: (2)
 
Fenderjack's Avatar
 
Join Date: Aug 2006
Location: North Point Creek, Md.
Posts: 4,330
Default

Rotella T.. Run it in everything..


John jr
Fenderjack is offline  
Reply With Quote
Old 05-28-2014, 05:31 PM
  #4
Registered
iTrader: (2)
 
Join Date: Aug 2011
Location: bel air, md
My Boat: 1997 Donzi 27 zx & Almost 35' Fountain
Posts: 2,735
Default

My buddy has an older Wellcraft with a 7.4 he runs the cheapest SAE 30wt he can find. Motor has over 700 hours on it and the only thing he has done to it literally is change the oil and a set of manifolds last year. The motor does have a hard life cause he's always boating with guys that have fast boats and often ends up doing some long tows across the bay at 30 mph...
Black Baja is offline  
Reply With Quote
Old 05-29-2014, 02:03 PM
  #5
Registered
 
Join Date: Jan 2002
Location: Further South East of Dome Island
My Boat: 1996, Donzi, 22 Classic 502
Posts: 1,862
Default

99 cent WalMart oil or $12.99 a qt VTwin, you will never know the difference. Basic engine, doesn't matter.
Pismo10 is offline  
Reply With Quote
Old 05-29-2014, 02:40 PM
  #6
Registered
 
Join Date: Jan 2002
Location: Further South East of Dome Island
My Boat: 1996, Donzi, 22 Classic 502
Posts: 1,862
Default

Originally Posted by Borgie View Post
Maybe in a stock Mercruiser 7.4, however this statement is false regarding racing engines.
If you will look more closely...."Basic engine, doesn't matter" and this is correct. No racing motor here.
Pismo10 is offline  
Reply With Quote
Old 05-29-2014, 05:04 PM
  #7
Registered
 
Join Date: Jan 2002
Location: Further South East of Dome Island
My Boat: 1996, Donzi, 22 Classic 502
Posts: 1,862
Default

Originally Posted by Borgie View Post
I did, and as such clarified. I like to make sure clarification is made if someone else happens upon this thread. Oil is one of the least understood topics here on OSO. Fwiw
It is least understood because it does not matter in 90%+ of motors but everyone like to think it does.
Pismo10 is offline  
Reply With Quote
Old 05-29-2014, 06:49 PM
  #8
Registered
iTrader: (3)
 
Join Date: Sep 2009
Posts: 885
Default

Originally Posted by Pismo10 View Post
It is least understood because it does not matter in 90%+ of motors but everyone like to think it does.
A flat tappet motor that has been sitting 6 years qualifies for the 10% it does matter on
motor is offline  
Reply With Quote
Old 05-29-2014, 07:16 PM
  #9
Registered
iTrader: (3)
 
Join Date: Oct 2007
Location: yorkville,il
My Boat: 31 american offshore,38 fountain fever
Posts: 8,152
Default

i would use a oil that still has a lot of zink or add some zddp just because it has not been run in 6 years,jmo.if it was a 96 or newer i would not worry about the zink.
mike tkach is offline  
Reply With Quote
Old 05-29-2014, 07:18 PM
  #10
Registered
iTrader: (3)
 
Join Date: Sep 2009
Posts: 885
Default

What he said................
Originally Posted by mike tkach View Post
i would use a oil that still has a lot of zink or add some zddp just because it has not been run in 6 years,jmo.if it was a 96 or newer i would not worry about the zink.
motor is offline  
Reply With Quote

OSO Sponsor
OSO Advertiser
OSO Advertiser
OSO Advertiser