This is one of the oldest myths in lubrication. The claim is that synthetic oil causes leaks in older engines or machines. Published engineering guidance is clear: synthetic oil does not inherently cause leaks and is compatible with common seal materials when the system is in sound condition. What often happens instead is that older seals are already worn, hardened, or damaged, and the switch makes those existing weaknesses more visible.
Older equipment may already have seal wear, gasket deterioration, or oil consumption issues. If a better-performing lubricant is introduced, the system's pre-existing condition becomes more obvious. That is different from saying the lubricant created the problem from nothing. In industrial conversions, special caution is still required where certain chemistry types — such as some PAG-based products — have known seal-compatibility limits.
Not automatically. Many older systems can benefit from properly selected synthetic lubricants, especially when temperature stability, oxidation resistance, or extended service life matters. The right approach is to review viscosity, seal condition, compatibility, and the actual equipment application before changing over.
Does synthetic oil create leaks by itself?
Generally, no. More often, it reveals existing seal wear or poor condition that was already present.
Thinking of switching from mineral oil to synthetic? Banesto can help you assess viscosity, seal compatibility, and suitability before conversion.
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