Synthetic oil gt40

[nautiquedave]

Am looking into using amsoil.What are the pros and cons Thanks

[bchesley]

RE: Synthetic oil gt40

Your thread title is synthetic oil gt-40, but your content is asking about Amsoil. I can't comment on the Amsoil but if you search for Royal Purple I have a thread with a response from the manufacturer on using it in a GT motor. I am planning to make the switch to Royal Purple because its the easiest to get for me. My local parts store keeps several cases of each W on hand. I have been running it in my Dodge Diesel for around 100k and really like it.

[DanielC]

RE: Synthetic oil gt40

PCM recommends conventional oil.
I recommend Valvoline VR-1 40W, and a Motorcraft FL-1A oil filter.
My GT-40 has 1975 hours on it with this combination.
Another 1998 Ski Nautique, with a GT-40, I take care of has 1367 hours on it.

[DavidF]

RE: Synthetic oil gt40

The GT-40 engine uses flat tappets. Conventional wisdom suggests that oil with zinc additive (ZDDP) be used on engines with flat tappets. Synthetics do not have zinc additive and most conventional oils do not. Valvoline VR-1 does and is what I use. The zinc additive prevents the oil from being sheared (squashed) out from between high load parts such as flat tappets.

[bchesley]

RE: Synthetic oil gt40

DavidF,

Read my thread on the Zinc levels of Royal Purple. I was using valvoline VR-1 until I found out that Royal Purple has the same zinc and some weights have higher Zinc levels. I have switched to RP. I am going to use their 30W in my V-drive too. I have already been using their ATF in my tranny for two seasons.

[WakeSlayer]

RE: Synthetic oil gt40

I have been running Mobil 1 15w50, in my 502 Chevy since I got it. It was suggested to me recently to switch back to a single weight conventional oil. Last year I finally installed a remote kit which uses the Ford filter FL1A. Any suggestions on converting back? And why would I do so. I am not a motorhead by any stretch so lay terms would be more helpful. I get all bleary eyed trying to read the multitude of oil threads that have been posted here in the past.

[TRBenj]

Re: RE: Synthetic oil gt40

Synthetics do not have zinc additive and most conventional oils do not.

David, Im not sure that is true. I have seen a few datasheets for synthetics and certain ones (like RP or M1 15w50) have levels of zinc that are comparable to the VR1, etc. Agreed that you have to be very careful when selecting an oil with a FT cam, though.

I have switched to RP. I have already been using their ATF in my tranny for two seasons.

Be very careful what type of transmission fluid you use. I know that PCM does not recommend synthetics in the transmission, at least for the direct drives.

Mike, that M1 youre using might be fine. If you can find the datasheet to confirm the zinc/phosphorus levels, that might give you some peace of mind. I want to say that your 502 is a FT engine- though Im nowhere near 100% certain about that. If it is and the ZDDP content of the M1 youre using is in the 1200-1400ppm range, you should be fine.

[scoke]

RE: Re: RE: Synthetic oil gt40

Some great info in this thread.

I used the VR-1 in my boat but Shell Rotella T 15w40 was my other option but nobody carried it at the time.

The Royal Purple has more zinc but the cost is quite a bit higher. For one oil change a season, it might be fine but if you are going to change your oil, 5-7 times a year, the cost adds up quick.

[bchesley]

RE: Re: RE: Synthetic oil gt40

RP is definately more expensive but yes its only a change or two a year for me. I have shared boat time with three friends. We probably ride 200 hours a year, but only about 50 on mine and spread out on the others. I usually have 25-30 hours with the wife and kids so I am not racking up major hours.

[bchesley]

Re: RE: Synthetic oil gt40

TRBenj,

You are correct, PCM used to say no to synthetics, but suddenly that is all you are supposed to use in their new tranny. Must have had a change of heart.

Brad

[WakeSlayer]

RE: Re: RE: Synthetic oil gt40

I checked Mobil 1's data sheet, and it shows 1200ppm.

[TRBenj]

Re: RE: Synthetic oil gt40

TRBenj,

You are correct, PCM used to say no to synthetics, but suddenly that is all you are supposed to use in their new tranny. Must have had a change of heart.

Brad

Not likely that it was a change of heart- Im sure there was a component change driving the recommendation in the V-drives. I can say with a lot of confidence that the older trannies (both PCM 1.23, 1:1 and BW 1:1) should not run synthetic.

[JUST-IN-TIME]

RE: Re: RE: Synthetic oil gt40

Only thing on asmoil is the corrosion inhibitors are skimped on
i noticed this on lower unit fluid more

[bchesley]

RE: Re: RE: Synthetic oil gt40

I have had good luck so far. I ran it in my old borg warner for a couple of summers too with no ill effects. I will be the test mule and see how far it will go.

[TRBenj]

Re: RE: Re: RE: Synthetic oil gt40

I have had good luck so far. I ran it in my old borg warner for a couple of summers too with no ill effects. I will be the test mule and see how far it will go.

According to PCM, you wont see a failure right away but it does decrease the tranny's life. From what I remember from my conversation with them, they were seeing failures in the 600-800 hour range when running synthetic. Its just too slippery. Over 1200 hrs on my '90 1.23 that ran 20w most of its life. I disassembled it to change to ATF 2 years ago and it still looked great... I will be sticking with conventional Dex/Merc per the recommendation of the manufacturer and other tranny experts.