One subject that is constantly discussed without coming to any conclusion is what engine oil to put in a 308.
The reality is that our 308s don’t get driven often enough or far enough to really make oil choice that critical. As long as it’s a quality oil, and the right weight, and changed regularly, the oil should be fine. For many people changing oil yearly, means less than 1000 miles on each oil change. That is not a lot of use to breakdown the oil. All oil degrades with use… the additives used to provide multi grade viscosity slowly stop working and the oil itself looses its shear stability (the ability to keep metal parts away from each other under high pressure). The oil may absorb some combustion by-products and even some coolant, depending on the condition of the rings and head gasket.
As with any religious debate, there are more opinions than solid arguments. One can choose to go with the oil Ferrari recommends now which is Shell Helix – a high tech oil made for modern high performance engines. One can choose an oil formulated for high heat and high pressure – (a so called diesel oil). One can choose a synthetic oil. One can choose a mineral oil. One can choose a narrow viscosity range. One can choose a wide viscosity range. One can choose an oil recommended on the Internet by a stranger without any further thought 😉
Some claim that these engines are old and were not made with the same tight tolerances as modern engines, and the oil choice should reflect this. Empirically this makes sense. Also, in many cases, these engines are already worn and so might be better served with an oil formulated for high mileage engines whose internal tolerances tend to get wider as they accumulate miles. One can choose an oil with high zinc supposedly to help lubricate tappets (cam followers). One can choose to use additives with an off the shelf oil to makes an essentially unknown and untested concoction. A number of people, including mechanics, claim synthetic oils cause increased leakage in these old engines and should be avoided. Other mechanics claim this is rubbish and synthetic oils don’t cause additional leaks.
At the end of the day, you pays your money and takes your choice, in the knowledge that the choice probably won’t make the slightest difference over the next 12 months/1000 miles.
My current oil of choice is Shell Rotella which is Shell’s diesel and truck formulation which is also suited to older, high mileage engines and, I think, a better fit for my particular Ferrari’s engine. It has high zinc so that box is ticked, whether it’s important or not. Again… even the need for zinc is contentious! Rotella is available in mineral (T4), semi-synthetic (T5) and fully-synthetic (T6) versions. When I switched a few years ago from mineral Rotella T (my old independent’s choice) to synthetic T6, I definitely had more oil weeping from seals and gaskets. So now I am going back to T4 which is the new formulation of the old Rotella T to see if the oil weeping stops. T4 is readily available in 15W40 weight which is perfectly fine for my summer driving in NY. It even comes in 2.5 gallon containers – exactly the right size for a complete oil change… yes, old Ferrari’s need a lot of oil.
One area where everyone should be able to agree is that we don’t know anything about the oil we poured in once we close the cap. Oil analysis can help here and will be the subject of a future blog post.
Disclaimer: 308restoration.com describes the restoration work I perform on my car and only my car. I am not a professional mechanic. The website content is presented for entertainment purposes only and should not by seen as any kind of advice, information, instruction or guidance for working on any other car. The opinions stated here are my own and no-one else’s.