NB: This information is given for guidance only and cannot engage the author's liability in the event of misinterpretation, failure to assess the vehicle's actual condition and/or non-conformity, unsuitable mechanical practice or the use of inappropriate tools.
Which oil for a Laverda engine? A clear answer to a sensitive question, after consulting the main oil companies.
What makes these engines special
- Air cooling: in sporting use or in traffic jams, temperatures can be high → an excellent hot oil-film strength is essential.
- Generous running clearances (and wide oil-pump tolerances) → high hot viscosity is essential.
- Rudimentary filtration (mainly by centrifuging in the crankshaft flywheels; the "filter" is only a strainer) → the oil must be detergent enough to prevent deposits building up in the flywheels, which could block the passages.
- Wet clutch → an oil suited to this, limiting plate slip and cold sticking.
- Moto Laverda originally recommended mineral Total Bol d'Or 20W50.
Conclusion: a multigrade motorcycle oil, moderate viscosity when cold (fast top-end lubrication) but not too thin (wide clearances), and high when hot (film strength). 15W50 is today's best compromise.
Mineral, semi-synthetic or synthetic?
Thanks to API standards, any current branded mineral motorcycle oil already exceeds the old Bol d'Or's performance. But synthetic oils offer far better hot film strength (Motul now recommends a 100% synthetic, 300V 15W50). Possible drawbacks of synthetics: high detergency (risk of loosening deposits in a poorly maintained old engine) and a molecular structure less suited to the wide clearances of worn/high-mileage engines.
Which oil to choose?
- Well-maintained engine, known history, clean, little wear: semi-synthetic such as Motul 3100 or 5100 15W50 — an excellent compromise.
- Fully rebuilt engine (modern parts, matched clearances): 100% synthetic such as Motul 300V 15W50 — maximum protection.
- Engine of unknown history, fairly worn, that blackens the oil: better a mineral 15W50, for the safety of a low-detergent oil.
Oil-change interval
Whatever the oil, the change must follow the manufacturer's recommendation (2500 km), because of the lack of a true filtration system.
Add-on filtration?
Adding a cartridge oil filter looks attractive but is not recommended (except on an engine rebuilt with a quality uprated oil pump). The system runs on a low-pressure / high-flow principle: the very moderate pressure copes poorly with the extra restriction a cartridge filter can cause.