Is it best to use synthetic engine oil in older engines?

There’s considerable debate around whether synthetic engine oil in older engines has any benefit, and indeed whether the lube may in fact cause damage to older engines.

Ask any classic or vintage engine enthusiast and you're sure to find a debate on whether synthetic or regular engine oil is better for older cars. Some believe there's no sense in changing what works, and mineral based oil has always performed well: Others argue that synthetic oil has better oxidation properties and is more stable across a wide
temperature range, which provides better protection for old parts.

What are the benefits to using synthetic engine oil in older engines?

A number one killer of engines, new or old, is temperature. Engine oil is used to prevent friction and heat from causing engine damage. If you have a vintage car or an old engine that needs to operate under colder temperatures, then crude based lubricants aren’t ideal.

Because regular motor oil’s viscosity isn’t as stable at higher operating temperatures the oil tends to have a higher viscosity to compensate, however this higher viscosity is a problem at low temperatures and on start-up. Although modern petroleum oils are formulated with sufficient additives to work in cold or hot climates, synthetic motor oil is more consistent and is engineered to function well at all temperatures even under extremes.

Since synthetic lubricants are engineered from chemicals, or highly processed crude the oil is uniform at a molecular level. Conventional oil is not always uniform, with molecules occurring in different sizes. Synthetic oils, due to their greater uniformity, last longer and still provide lubrication at much higher temperatures. That’s why synthetic engine oil in older engines can also reduce “blow-by” and reduce emissions.

Petroleum based lubricants occur naturally and are refined then processed with additives before being distributed to users. Unfortunately undesireable elements such as waxes and sulphur occur naturally in crude oil and even when highly refined are still present to some extent. These are harmful to any engine. However synthetics, being chemically engineered do not contain any of these harmful contaminants which again means that using synthetic engine oil in older engines is extremely beneficial.
Synthetic oil generally tends to cost more per unit than conventional oil, although the gap is rapidly closing. For the penny-pinching types, this higher expense may cause a bit of irritation. But this expense difference needs to be assessed in context. An engine breakdown due to overheating or a part breaking will cost significantly more than the price difference in using a synthetic oil. Also oil change intervals can be extended so there’s a cost saving not only in the oil, but also in disposal and labour costs. So when considering whether to use synthetic engine oil in older engines it’s wise to not only consider the up-front costs.

Are there any dangers to using synthetic engine oil in older engines?

Some Polyalphaolefin synthetic oils aren’t compatible with certain types of plastics/ rubbers used in oil seals and can result in oil leaks. Also if you have an older car, don’t fill with the modern ultra low viscosity motor oil: Chances are you’re not going to have sufficient lubrication of the high-load components such as big end bearings.

There are definitely benefits to be had switching to synthetic engine oil in older engines, but you need to make sure you use only quality lubricants; such as those supplied by Habot Synthetic Lubricants. Call us for professional advice on which oil best suits your requirements.