synthetic oil

[todda]

Hey, anyone out there using synthetic or synthetic-blend oil with their oil-changes? Anybody hear of any plus/or minus to using synthetic in the
GT-40 or any contraindications? Just curious as it is time for my oil change...

thanks!

[NautiqueJeff]

RE: synthetic oil

[83sn2001]

I have ran Mobil 1 in the past in my 95 mastercraft. I contacted Indmar when I first purchased the boat and they informed me basicly that it would not hurt but that it wouldn't necessarily help either. He told me specifically not to use it or any additives for the first 100 hrs as the synthetic oil would prevent the engine from proper breakin which tells me that it is slicker than conventional oil. I ran it for 2 years with no problems. On the other hand I put 900 hrs on my 89 Marlin Skier (mercruiser gm block ) with 30wt/hd Pennzoil.No problems. The engine marinization companys (Indmar, Pcm, Merc.) have contracts with oil companies and they will not recommend any oil other than these companies. The 83 ski I just purchased has Mobil 1 in it now. I haven't decided if I am going to stay with it or not mainly because of expense. I personally don't see the harm in using either as long as you keep it changed every 50 hrs

[jedgell]

Is there any benefit to running a straight 30 or 40 wt oil vs a multi-vis oil like 10-40? Just curious why PCM would recommend the straight wt oil for the GT-40? Is it a higher grade of oil?

[83sn2001]

Oil viscosity is usually determined by geographic location in relation to engine clearances. I have a freind that had your exact same boat, he ran synthetic in his so his experience would be different. In your area I would stick with straight 40.

[jedgell]

I'm planning on moving to Montana next year, should I use the 10-40 then? I think you're only supposed to use straight wt 40 in 60 deg or warmer. Almost certain to be some colder days than that in MT.

[83sn2001]

That is what I would probably do. I would give PCM a call to make sure

[j2nh]

There was a time in the early 90's when Indmar offered and extended engine warranty in Mastercrafts provided that you used Mobil 1 and followed the manual on oil changes. I think you also had to send samples in at every oil change for analysis.
People spend endless hours arguing about synthetic vs dino oil.
I would imagine that if ANY of the engine companies recommended synthetic their competitors would have a field day.
Hard to argue against a higher quality oil provided that you still maintain the same change interval.
Mobil 1 is the factory fill on:
Porsche, Mercedes and VW.

[NCH2oSki]

All Snythetics meet or exceed manufacturers recomendations. I use them in my CC and did use them in my MC. I still change them at the recomended intervals. I have never had any problems, nor do I expect any oil related problems.

[todda]

Thanks Jeff for the manual rec. Funny, I did go straight to my manual just after I hit send on this post and saw the same thing. I was just curious overall, but I think I will just stick to my straight 40W up here in Washington, seems to have had no problem as of yet.

[ozark_skier]

What about oil filters? Does anybody know who really makes the PCM filter?

[SGY]

Jedgell. I spoke with PCM on the issue of straight weight vs. multi weight oil. The tech told me that the multi weight oil is recomended in the Excalibur and straight weight in the GT-40. The reason is different oil pump in the newer GM block. Right now I'm running straight 30 weight in my Excalibur--due to my mechanic's bias against the multi weight oil. I'm going to drain that oil and put in the recomended oil shortly, however. The PCM tech indicated that the only problem with the straight weight oil is hard starting when cold--but we are talking "cold", not 50 or 60 degrees F. The tech said just let the boat warm up before hitting it hard with the straight 30 weight.

Interestingly enough, Taylor Boats in SLC Utah recommends a 20/50 synthetic.

[jedgell]

Thanks SGY, that's the answer I've been looking for. Up until now, no one has told my why to use the straight wt oil. I've already bought the straight 40, plan on changing it this weekend.

[SGY]

jedgell. Just so you know, my mechanic, who's been in the biz for lots of years (30), doesn't use the 40 weight unless its going to be really hot. You are in Houston, so I think that qualifies.

Just be sure your boat is up to operating temps before putting the hammer done. That 40w oil is pretty thick until it heats up. The hint I got from PCM was that the multi weights are much better these days but if it weren't for the change in oil pumps, they would be using the straight weight oil on the GM motor. They didn't come out and say that but its what I inferred.

Good luck.