Ok there is a lot of talk about what oil to use but I am still unclear. I have a 1970 Fiat 500 and I'm not sure what oil to use. I have read in a manual I found online to use 15w40. Is this correct? When I look up 15w40 they all say for diesel. Can someone guide me to the right oil, brand. I'm located in the usa and would really appreciate your help.

Most people on this Forum seem to go for 20W50 and use a specialist classic formula of oil. This will have levels of anti-wear additives similar to those available when the engine was designed. There are also some arguments for using special motorsport oil formulations.
My manual recommends 15W40 for the later 652cc engine.
I have read quite widely that even the more modern diesel oils are likely to have more anti-wear additives than petrol formulations. It seems that the camshaft and its lifters are the most vulnerable parts if you get the choice of oil wrong.
This is a link to a well-informed, very readable article on the subject.

http://www.superchevy.com/how-to/corp-0808-worn-down-engines/

For the bulk of 500s, a good quality 20w/50 oil is a sound choice. I don't know where you are in the USA, but Exxon/Mobile (Esso), Pennzoil, Castrol all do this specification of oil (as do, I expect, a number of companies that only market/sell in the USA). If you are living in a very hot part of the USA, it might be that you have to go to a 15w/60.

So if I go with a 15w40 oil is that a diesel oil because when I search it it show all diesel oil. Or is there a speacial one I need to get. By the way I live in Florida. I just wanna use whatever is recommended. What brand/ type of 15w40 do you recommend?

With you being in the US, we being in the UK and me not being an oil expert, it's probably best to take the advice where Tom's and my suggestions overlap...ie, go for a "classic" 20W50.

As far as I can see, Pennzoil/Quaker state oil is available in Florida. My recommendation is that you use the "Pennzoil 20w/50" oil in the engine. If Castrol in available, use their 20w50 engine oil as an alternative. This is the specification that the bulk of the 500s over here use, and a sound choice. I would also recommend that the oil is changed annually, and as part of the oil-change routine, you remove the oil-filter cover (at the back of the engine) and clean it and the belt pulley of the gathered 'gunge' (which is what it is designed to do).

Ok first I would like to say thank you so much for the help and your time. Let me just make sure I get this right so use a 20w50 oil. Would that be a regular engine oil, a synthetic blend, or a mineral engine oil.

This topic has been thrashed out many times on here and as far as I know there has never been a consensus.

Oil, as long as the spec is correct for the vehicle is oil. The differences between grades and manufacturers is not as much as many people think. I used to work for Caltex (a joint venture between Texaco and Chevron) here in NZ and we used to sell a lot of oil. A lot of it was the same stuff in different bottles; for example we used to sell a general, cheap, put in your oil can to stop the door hinges squeaking type and another very expensive bespoke blend specified for a certain model of air compressor..... It was the same stuff!

That being said there is an additive called ZDDP that is important for lubricating the camshaft and the flat tappets in an engine. Basically it is zinc. There are of course a lot of other secret herbs and spices that oil companies put into their oils for specific reasons, but again, the difference between brands is not that much.

The moral of this story is that as long as the oil you get has the right viscosity, and the right additive package it will be fine.

My two cents
Chris

IM so lost about what oil to put in the fiat.

Use 20w50 oil. You can use regular, synthetic blend, or full synthetic. It really does not matter that much for these engines.
I also add a ZDDP additive. ZDDP, which is a zinc additive, used to be put into motor oil all the time. It was added to help protect flat tappet type lifters. It was eliminated from motor oil when catalytic converters started to be used in the USA in 1975. It was not good for catalytic converters. There were other additives added to oil to replace ZDDP, but they were not quite the same. This Rislone product adds this back. It is not expensive and you only add a small amount per quart of oil.
So to review. Use 20w50 oil of any type. Add a Zinc additive into the oil following the instructions on the bottle. You can buy this at just about any auto parts store.
John (I am in the Nashville, Tennessee area)

Thanks John. Will do.

Hi Napolikidd, the 15w40 you're probably talking about is the Rotella T4, yes it mentions for diesel engines but a lot of people use it for regular gas cars. If I remember well Subaru owners love that stuff.

jjacob, interesting about the zinc additive, I'll have to look into that.

Ok so I could use the 20w50 with the zinc additive. Or if I wanted to use 15w40 I could use the Rotella t4 that is use for diesels and would have no problems. Am I right? is this the right Rotella you have mentioned?

https://i5.walmartimages.com/asr/0e....jpeg?odnHeight=450&odnWidth=450&odnBg=FFFFFF

Yep that's the one I picked up as well and plan to use on my next oil change.

Also there are tons of classic porsche owners who use rotella and delo (chevron) diesel oils in their cars because they still have additives like zinc in them.

Seems to be some consensus that the T4 being a diesel oil is less affected by new emissions and oil regulations regarding zinc, so it's one of the few oils with zinc in them.

There's a lot of discussion about it, including not needing to add a zinc additive with this oil because it already contains it:

https://landroverforums.com/forum/discovery-ii-18/rotella-plus-zinc-additive-84540/

https://landroverforums.com/forum/discovery-ii-18/rotella-plus-zinc-additive-84540/

http://forums.pelicanparts.com/porsche-911-technical-forum/933893-shell-rotella-t-15w40-users.html

http://www.binderplanet.com/forums/index.php?threads/rotella-t3-is-out-and-t4-rotella-is-in.134753/

https://bobistheoilguy.com/forums/ubbthreads.php/topics/4352970/Question_about_SHELL_ROTELLA_T

Shell actually wrote this:

We would certainly recommend Rotella T4 Triple Protection 15W-40. You're right, it contains 1200 ppm of zinc and provides anti-wear protection for gasoline engines with flat-tappet (solid) lifters. Hope this helps! - The Shell Rotella Team

Click to expand...

Some good reading material, but it seems the T4 should give good zinc amounts, without having to resort to a zinc additive

Seems like rotella t4 it is. Thanks :slayer:

Hi Guys . I wouldn't over complicate things. I am sure these engines will be ok on any 20/50 20/40 or any similar quality multigrade oil. In Italy I bet they shove almost any oil in, I think these engines will be very tolerant of the viscosity and quality of the oil.I have a Mini a Frogeye and a 72 500 L and they all get the same oil. I also have a modern car which gets vehicle specific oil.
KEEP IT SIMPLE

Called a buddy in Italy and he said Castrol GTX 20w 50.

If you have a standard 500, Castrol 20/50 is as good an oil as you can put into these wee beasties. The ZDDP additive, in the recommended doseage, will do it no harm and probably a lot of good.