OIl/Trans fluid

I've been reading some posts on different types of oil and the additive requirements. Can anyone give me a short list of the best oil and weight to use for a 99 GT40. I'm in SC. Also, anything special about the transmission fluid? Is it a best practice to change both when winterizing or is it OK to change them close to the end of the season and then still put some hours on before winterizing?

Dex III is backwards compatible (OK to use). I believe schedule is 100 hrs for tranny.

a0128 wrote: For your 1999 GT-40 you will want to use an oil with a high zinc concentration. A ZDDP number of 1400 ppm is best. I use Valvoline Racing Oil 20W50 in my GT-40. I believe the original recommended oil was 40W40.

The manual does recommend 40w40 although I don't know if that's GT 40 specific? It also lists 20w50 for below 32 degrees temps. Just wondering why you choose 20w50 other than valvaline racing not being available in that weight?

I use Mobil 1 15w50 every 50 hours with Mobil 1 filter as well.

Castrol Transmax Dex/Merc every 100 hours

Mobil 1 15w50 and any dexron compatible trans oil every 50 hours on both.

Toertel wrote: I use Rotella T 15w30 (right Zach?) and Dex 3 Oil and filter every 50 hrs and Dex every 100

See close enough...I did not have the can infront of me.
I buy it at WallyWorld

I give up

Cumby wrote: I decided to contact PCM. Their recommendation for oil was the Rotella 15w40.

Glen,
What brand of car(s) do you drive? I'm just wondering if you've called GM, Ford, Chrysler, etc. regarding the brand??? I feel you should call PCM back and get the recommendation is writing. You talked with someone and got a PERSONAL opinion!!!!

I use Royal Purple HPS™ – High Performance Street Synthetic Oil in 20W-50 for the engine. I also use the K&N oil filter (number 3001).

The topic of ATF will likely get a little debate. Friction modifiers, synthetic vs. non-synthetic, etc. Lots of folks here use Valvoline Dex/Merc ATF.

JQ

Glen,
The brand comes down to your choice but the key is to make sure it has the proper levels of ZDDP. I've been running Valvolene racing 20-50 in all my boats for years.

8122pbrainard wrote: Glen, The brand comes down to your choice but the key is to make sure it has the proper levels of ZDDP. I've been running Valvolene racing 20-50 in all my boats for years.

So weight doesn't matter??? I've seen a lot of different personal opinions on different weight oils. That's why I went back to PCM since I didn't see much/any available in 40w40.

8122pbrainard wrote: Jonny Quest wrote: I use Royal Purple HPS™ – High Performance Street Synthetic Oil in 20W-50 for the engine. JQ Rob, Doesn't the work "street" indicate there isn't ZDDP added? Is there any and do you know at what levels?

I don't know the specific ZDDP additive level. Based on Royal Purple statements, the oil does contain zinc and phosphorus. To quote from the Royal Purple website:

"Royal Purple HPS Series motor oil is specifically formulated to maximize performance and meet the demands of high performance and modified engines. HPS is recommended for vehicles no longer under manufacturer warranty and for those seeking a higher level of performance and protection. This unique blend enables HPS to outperform leading synthetics and conventional lubricants for both gasoline and diesel engines. Royal Purple’s HPS is fortified with a high level of zinc/phosphorus anti-wear additive and Royal Purple’s proprietary Synerlec® additive technology."

I like the Royal Purple stuff. I've also used Mobil 1 Racing in 15W-50.

So why do you guys choose a 50 weight oil when 40 was the original recommendation? Is that based on anything objective, or just preference?

oil is such a hot topic, you should visit a Harley Owners site some time. people about kill each over this topic.

Im guessing those running 20/50 are using synthetic which flows much better than conventional oil, likely the reason for the heavier weight over the 40.   

These engines work hard, much harder than car engine.   I would guess that 15/40 Rotella or 20/50 pure synthetic would be the best oils to use.   

EPA controls the additives in oils.   I'm guessing that oil branded as Racing likely circumvents EPA as does Diesel oil. Anyone know of any facts around this?