Type of oil to use

[mdrburchette]

I'm sure Dave is running Shell Rotella, which is fine for the engine. The viscosity you use depends on outdoor temp variations so I'm sure we all use different variations. My 72 owners manual recommends different viscosity oils depending on outside temperature, from SAE 10 weight to 40 weight. In a multigrade oil, the first number (10W) in a 10W30 will tell you what the lowest outside temps can be to maintain a 30 weight viscosity. The second number gives you the higher temp range. So a 5W30 is good for a longer range of temps than a 10W30. Most of us, who use our cars for just the summer months, can run a straight weight oil. The zinc content is more important for our older engines. I'm running straight 30W in my old worn out engine and higher grade race sythetic in my higher performance engine.

[pope]

Our Fiat spiders are tappet engines that need extra protection from when the cam slaps the tappet cup. Modern engines use roller or sliding tappets that are in constant contact with the cam, thereby only needing a good lubricant to operate. The Fiat tappet is not in contact with the cam more than half of its rotation. The lobe comes around and contacts (slaps) the tappet several thousand times a minute causing wear from friction. To remedy this, Zinc dialkyldithiophosphate (ZDDP) was added to motor oil to act as a soft metal barrier between the friction parts. It does its job well.
Almost all modern oils with a lower viscosity than 15W-40 ( meaning all 5W and 10W-30/40 oils) have had ZDDP virtually engineered out of it over the past few decades because it is not needed in todays modern engineered engines.
Fiat Twin Cams are not modern engines and still need this. The only reason I brought up other viscosities is that if you are using them, there is not enough ZDDP to be of any beneficial use.
It is like a line in the sand. 15W-40 and above it has it, 10W-40 and below has virtually none.

Now you can use what you want, but for the same cost, why not use what was designed for your engine and reduces engine wear greatly.

[launieg]

Thank you everyone for a very good discussion. I was unaware of these oil differences. When I was in my twenties, oil was mostly single viscosity, and we used 10w when the car was pretty new, and 30w if the engine was getting old, simply because we figured it was thicker most of the time and wouldn't slip past the rings as easily. It was stiffer than molasses in the prairie winters of 30 below! (Where I live now, it rarely goes below freezing.)

More importantly, I was completely unaware of the zinc issue, which makes sense. Now I know! I'll be putting the right stuff in it now, and saving my engine wear.

[pope]

In a multigrade oil, the first number (10W) in a 10W30 will tell you what the lowest outside temps can be to maintain a 30 weight viscosity.

Sorry D, I am just trying to make sure the others understand this.
I know that some of you are reading this, so I just want to clear up a little thing about oil so that we are all on the same page on this. All season, multi weight oils expand the temperature range that the oil can be used safely. Ex. 10W-30, The "W" stands for winter....not weight (common misconception). In the winter, the oil is a 10 weight oil in very cold conditions until it starts to warm up and then becomes a 30 weight oil. This is achieved with additives that change their shape as they warm up. It is not a 30 weight oil throughout the entire temperature range. Same with a 0w-30 and 5w-30, they allow the oil to flow as a 0 weight and 5 weight oil when cold ( and when I mean cold, I mean subfreezing) and then as a 30 weight as it warms up. This allows oil to flow in an ice cold engine that would normally produce oil so thick that it would not flow at startup.
0W-30 flows at cold temps that give 5W-30 problems and 5w-30 flows at cold temps that 10w-30 has trouble with.

[mdrburchette]

[quote="pope"]
Sorry D, I am just trying to make sure the others understand this.
quote]

No problem, Pope. A better explanation is always appreciated.

[TulsaSpider]

Wow! The things you learn on here....... Thanks guys!

[So Cal Mark]

Tappy needs to read these threads

[TulsaSpider]

That's where I first ran across this info. I wish him luck methinks he needs it!

[Tappy]

I've read it and learned , after i get the head back on i'll change the oil right away , and so the oilfilter thats ont it as long as i got it

might as wel get the oil pan of for inspection first , it needs a new seal also first need to search out wicht gasket i need becouse its not a genuine spider motor