Castrol Full Synthetic Gearlube

[NathanY]

Is it a real synthetic? I bought some for my lower unit, to replace the dino-oil. It was same price as Penzoil regular l/u lube, so I thought I'd give it a try. I usually use Quicksilver l/u lube, but after reading all the info here, I thought I would try a synthetic. I hope this is a synthetic anyway.

 

[rabidfish]

Re: Castrol Full Synthetic Gearlube

It probably is fully synthetic... But i wouldn't use it in my lower unit, here's why: Most marine lubricants have formulas that allow it to work well, even if it gets water in it (to a degree). Most automotive applications have no such formula. If they get water, the water will prevent the lubricant from sticking to the bearing surface ( guess where this is going... )<br />The marine engine manufacturer's all have at least partially synthetic gearlubes. Stick with one of them. Mercury ( Hi-Perf ) Evinrude/Johnson (HPF) or Volvo (GL5). I am certain Yamaha, etc... has one also.

 

[NathanY]

Re: Castrol Full Synthetic Gearlube

But the bottle say "Specificly designed for marine stern drive and lower units" So do I need to change it again or what?

 

[rabidfish]

Re: Castrol Full Synthetic Gearlube

I wouldn't change it... Try it & let us all know how it works out! That kind of feedback is worth it's weight in gold!

 

[bubbakat]

Re: Castrol Full Synthetic Gearlube

Nate I use what you are fixing to use and at the end of summer when I change it out it comes out in good looking shape. I changed it on my 85 h/p the other day and the magnet didn't have the dust on it usually has.

 

[Bondo]

Re: Castrol Full Synthetic Gearlube

I run either Mobil 1 75W-90,<br />Or Penzoil 75W-90....<br />Both Full Syn.....<br /><br />Had a Bad Seal on my drain/fill plug, took on Alot of Water.......<br />Even the Sludge was Very Slippery.... No Damage.... Changed to oil,+ Went........

 

[sangerwaker]

Re: Castrol Full Synthetic Gearlube

Nate,<br />I have been using that stuff in 2 different boats for 2-1/2 years. Never a problem. I'm not sure if it is truly a full synthetic, but it sure has the synthetic "smell" when you drain it. Good ol Wally World sells it up here, and is about $7 per quart. Since most of us only change that fluid once per year, $7 is pretty cheap insurance.

 

[SS MAYFLOAT]

Re: Castrol Full Synthetic Gearlube

I put it in my outdrive about 3 years ago. Its still working for me. Lube is in good shape during its seasonal changing. I do know my outdrive does run quieter with it.