|
Unless you boat in cold weather, I would use a straight 40wt or a 15-50 or 20-50. Merc oil is a 25-40w and is now a semi synthetic.
|
STP and those type of oil additives are nothing more than a polymer with some base stock and maybe a very slight treat of additive.
Adding it to a straight weight oil(30) could bring the viscosity up to a 40 but the polymer that is used in STP is a inexpensive one so ove a short time the polymer will shear and you will have a straight 30 again. (The oil can shear any less than a straight 30 because straight weights have no polymers.) Instead of running a straight 30 w/ an additive use a straight 40,(if you want to stay with a straight weight) if not use a good multi-viscosity (20w50 comes to mind) motorcycle oil. Ken |
Originally Posted by jayhawk261
(Post 2566328)
The car in that avatar is a production 1993 Mustang Cobra. They only made that model one year. I think they had about 5 - 10 more hp than a stock GT, and had a different body kit. They still seem to bring big money in good shape. There were some R versions available to race teams only I believe. They were a no air, no power option deal, and they were stripped down for weight.
|
Originally Posted by 07DominatorSS
(Post 2565771)
You should run a 10w-40 or a 20w-50, or something in that range.
That particular multi weight oil breaks down faster than anything else. Mercury recommends straight 40w, 25w-40, or 20w50, if I'm memory serves me correctly. Read here: http://www.mercurymarine.com/service...qs/fueloil.php This thread contains some interesting reading too: http://www.boatengine.net/t/055289.html I'm a big fan of synthetic oils, but that's not what we're talking about. |
Originally Posted by fabricator
(Post 2566423)
NEVER, EVER use 10w40 in ANYTHING GM powered. :hitfan:
That particular multi weight oil breaks down faster than anything else. Mercury recommends straight 40w, 25w-40, or 20w40, if I'm memory serves me correctly. Read here: http://www.mercurymarine.com/service...qs/fueloil.php This thread contains some interesting reading too: http://www.boatengine.net/t/055289.html I'm a big fan of synthetic oils, but that's not what we're talking about. |
A 10w oil starts out as a base 10 weight oil, and a 20w oil starts out as a base 20 weight oil, put simply. The polymers that are used to create the '40' in the 10w40 oils breaks down faster that those used in the 20w40 oils. Oil chemistry is very complicated, and I won't pretend to be an expert. OilDoc does a good job of explaining oils in this thread: http://www.boatengine.net/t/055289.html
|
Thanks i think ill go with 20w40. the avatar is actually a picture of a car like mine i just sold. Jayhawk explained exactly what it is. They did come out with gt-40 heads stock. with a blower and exhaust they are a 400 horse at the rear wheel car.
|
Royal Puple straight 40 weight
|
Originally Posted by firehawk
(Post 2565724)
What type of weight oil should i run a 454 merc 330 horse motor.
30wt (if ambient temps at or around 40*F) 40wt (RP;Kendall; Castrol; Penzoil etc) 25W-40 (Mercury Semi-syn) 15W-40 (Amsoil Marine); Rotella;DelVac 15W-50 (Mobil-1) Silver Cap 20W-50 Mobil-1 V-Twin; Amsoil; RP; Redline; Castrol; Kendall etc.) My choice for your engine: Mobil-1 SilverCap 15W-50 $24.00/5 qt @WallyLand Why? A lot of boaters on this board use it and tear down looks real good. Mobil-1 V-twin 20W-50 if you can go $9/qt or Redline 20W-50 have the highest levels of anti wear additives I have seen so far. |
| All times are GMT -5. The time now is 10:15 AM. |
Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.