Motor Oil and Trans Fluid for GT-40

[Jesse13]

I have a 98 AN and I am getting ready to change my fluids and the Manual is telling me to use 40W40 for the motor and DEXRON III for the trans.

I went to a few automotive stores and was unable to find these. From what I was seeing, it seem as if these may be obsolete. Are they in fact obsolete or are they just common to the marine industry?

If they are obsolete, what are some recommendations for each?

[Chexi]

RE: Motor Oil and Trans Fluid for GT-40

You can get straight 40 weight, but it is hard to find. There is another weight that works well according to many of the members. I believe it is the 20W50, but someone else will chime in and confirm or deny. You must use oil with ZDDP in it. Valvoline VR1 has it, as well as a few others. Your local Autozone should carry the Valvoline 20w50 VR1 (or at least mine does). I have heard that Carquest carries the straight 40w VR1, but I have not had luck here in Dallas.

Autozone also stocks Valvoline Dexron III. Others may as well.

[DanielC]

RE: Motor Oil and Trans Fluid for GT-40

Use Valvoline 40w VR-1 oil. Use a Motorcraft FL-1A oil filter. I was able to get the oil filter at Wal*Mart. They are also available at any Ford dealer.
Dexron III and Dexron IV ATF has been discontinued, there is now a Dexron/Mercon formula available for the transmission.

[bchesley]

RE: Motor Oil and Trans Fluid for GT-40

I use only valvoline VR1 40W. It has the right addititves that our old style flat tappet motors need. There are others but I can easily find the valvoline. Anyone who carries valvoline can order you some.

[Sinkoumn]

RE: Motor Oil and Trans Fluid for GT-40

Valvoline VR-1 40W oil, and a Motorcraft FL-1A here as well - I get my VR1 from L&M Fleet supply in northern MN (I can't find it anywhere in Minneapolis at any major (read: chain) oil store)

[east tx skier]

Another Valvoline VR-1 user here, but I use the 20W50. Motorcraft FL-1A. Dexron III.

[Teleman]

I have heard some that use 15W-40 too. I use 40 from west marine (4 quart jug, easy to carry), or in the summer you can find it at car stores. Motorcraft FL-1A here too. Cheap and easy to find. Trans fluid out is a pain. I found that a shampoo pump seems to be the easiest. Included with the bottle and disposable too. Quick rinse before use and pump out 2 two qts. I have yet to see a engine fail beacuse of the wrong name oil. I run my 93 yota on Super-Tech walMart oil (Cheap) and have 260K miles on it. Not even a puff of blue at the bottom of hills. I realize boat is under more stress than car, but change oil after 50 hrs and it will be fine. When was the last time you heard of someone siezing their engine (Or even hurting the engine) cuz they used X-Brand oil?

[jmo]

I run Castrol GTX 15W-40 with my GT40 and it purrs all season as I go from Spring 50 degree water & air temps to Summer 90's and then back to the 50's in the Fall. It is SH rated and contains 1300 ppm of Zinc, which is only slightly less than the 1400 ppm the valvoline VR 10W-30 has.

I think your GT40 will be happy with either, but if its never cold where you are then the Valvoline VR1 straight weight 40 is probably better.

[Hollywood]

I just looked on Castrol's site and it doesn't show the Zinc content for their GTX line of oils.

[jmo]

I just looked on Castrol's site and it doesn't show the Zinc content for their GTX line of oils.

Did you look at the spec's for the 15w-40 diesel? It's all in there, I realize the general literature doesn't explicitly call it out, but if you look at the actual specs you will see the Zinc level of 0.13 and SH rating.

http://www.castrol.com/liveassets/bp...GTX_Diesel.pdf

[Mikeski]

Before I answer this question I usually ask another question...

Do you let your boat warm up before you bring it up on plane? (hopefully face to face so I get an idea if they are telling the truth)

If the answer is yes then I am happy to recommend the straight 40w.

If the answer is, hmmm, well, I think, gosh I don't remember... then I recommend a multigrade. Bearings in cold motors don't like being pushed when they are cold running on straight 40w. That said, I have never heard anybody have any issues running either. Some dealers use the 15w-40 so they only need to carry one type of oil. It seems to work. In my GT-40 I always warmed it up and I always ran straight 40w, back then I ran Chevron 40w cheapo at the recommendation of a Chevron lubricant engineer co-worker. I no longer work for Chevron and now I have a Chevy. Now I run Chevron Delo 15w-40, 1600ppm zinc if I believe one website, 1380 if yo believe another. I have always run Dino oil.

[Hollywood]

Did you look at the spec's for the 15w-40 diesel?

No, I was looking at the regular line of GTX which doesn't even come in 15w-40. That should have tipped me off I was in the wrong place!

Thanks for the info.

[Sbt3]

I've always used the Mobil Delvac 15w-40 and had no issues. http://www.mobil.com/USA-English/Lub...1300_Super.asp

anyone see any issues with this? I've got probably 400 hours using it seems ok.

[mf01]

Shell Rotella 15w40. It can be picked up at Wal-Mart. It has the same zinc levels as the other oils listed.

[east tx skier]

That surprises me about the rotella. I haven't looked at it since I switched from it over to the Valvoline, but the Rotella 15W40 was one of the specific oils mentioned back in the many threads on the subject around the end of 2007 or that had lowered its zinc levels.