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How to use chainsaw bar oil

Updated: 22 October 2026

The tank is empty, the saw is on the bench, and you are not sure which cap takes the oil. This is how to use chainsaw bar oil on a petrol saw or a cordless one before you cut a branch. You fill the bar tank only, you prove the chain is throwing oil, and you stop if the pump stays dry after a simple clean. Which bottle to buy stays on the [bio chainsaw oil comparison](/hub/forestry-tools/chainsaw-oil-bio). Products Compared used Husqvarna’s UK lubrication check, Stihl’s UK fill notes, and HSE leaflet INDG317. This is not a felling course, and we did not test these saws. A qualifying purchase can earn a commission at no extra cost to you.

The tank is empty, the saw is on the bench, and you are not sure which cap takes the oil. This is how to use chainsaw bar oil on a petrol saw or a cordless one before you cut a branch.

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Liqui Moly Liqui Moly 1280 1 litre

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Stihl Stihl BioPlus 1 litre

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Stihl Stihl BioPlus 1 litre
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On this page
  1. 1.Fill the bar tank, not the fuel
  2. 2.Prove the chain is getting oil
  3. 3.If the chain stays dry
  4. 4.After the cut

Fill the bar tank, not the fuel

Switch the saw off and let it cool before you open a cap. On a petrol saw, find the oil symbol rather than the fuel cap. Fuel is the petrol mix. Bar oil is the separate tank. On many cordless and electric saws there is no fuel cap at all, and the chain still needs oil every session. Stihl’s UK guidance is the same fill for petrol, cordless, and electric saws. Do not fill to the brim. Leave a little room, fit the cap, and wipe any spill. Wear gloves near the chain. If you are about to fell a tree or climb and you are not trained for that job, oiling the chain does not make the cut safe. Which bottle belongs in the tank is the bio chainsaw oil buying guide.

Prove the chain is getting oil

A full tank is not proof that oil is reaching the chain. With the chain brake off, hold the bar tip a few centimetres from a light stump and rev the engine, or run the motor on a cordless saw, for a short burst. A line of fresh oil means the oiler is throwing. No line means you are about to cut dry. HSE’s chainsaw leaflet for work asks you to check lubrication before use and again through the day. Do not follow a workshop page that tells you to use engine oil instead. HSE says discarded engine oil is a poor chain lubricant and a skin concern with regular contact.
Oregon Oregon O10-6362 1 litre

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Oregon Oregon O10-6362 1 litre
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If the chain stays dry

If the tank is empty, you have not got a pump fault. If it is full and the test surface stays dry, stop and clear the oil hole and the groove in the guide bar. Dust and resin block them, including after a biodegradable oil has sat since last winter. Clean the hole, refit the bar as the manual shows, and repeat the stump test. If the paths are clean and the pump still delivers nothing, stop. That is a dealer job. Do not thin the oil with petrol, and do not keep cutting on a dry bar. Kitchen oil and neat rapeseed oil are not a fill.

After the cut

Cap the tank before you put the saw away. Do not rinse oily sawdust into a drain, and do not pour leftovers down the sink because the label said biodegradable. Oil Care treats waste biodegradable lubricant as hazardous waste. Oil that has reached a pond, a ditch, or a road drain is an incident, and bio chainsaw oil near water is the place for that duty. If you will not use the saw for months, do not leave a half tank of vegetable-based oil. Clean the bar, because that oil can oxidise and stiffen the chain, then keep leftovers in a capped, labelled container.

Common questions

Which cap is the oil cap?
On a petrol saw it is the cap with the oil or chain symbol, not the fuel cap. Fuel takes two-stroke mix. The oil cap feeds the bar. On a cordless or electric saw you may only have the oil cap, and that tank still has to be filled. If you are unsure, stop and match the symbol to the manual rather than guessing from the smell.
Do electric and cordless saws need bar oil?
Yes. The motor does not oil the chain. Stihl’s UK notes use the same bar-oil fill for petrol, cordless, and electric saws, and they tell you to look at battery and mains saws on a schedule because you are not topping up fuel at the same time. An empty cordless tank is an easy way to blue the bar.
Can I use old engine oil on the chain?
No. HSE INDG317 says discarded engine oil is a poor lubricant for a chainsaw chain and a skin-cancer concern with regular contact. Fresh mineral bar oil and formulated bio bar oil are the products sold for this tank. Oil drained from a sump is neither of those.
Should I thin thick oil with petrol?
No. Petrol in the oil tank is a fire risk and a way to wash lubricant off the chain. If the oil will not flow, check that you have bar oil of the grade the saw maker allows, and that the hole is clear. A pump that still will not deliver is a workshop job.
What do I do with oil left in the saw over winter?
Do not store the saw for months on a half tank of vegetable-based oil. Clean the bar, because that oil can oxidise and stiffen the chain, and biological oil that resins can seize a pump. Keep leftovers in a capped, labelled container and take them to a site that accepts waste oil. Do not pour them away.

Related pages

Bio chainsaw oil vs mineral

Best biodegradable chainsaw oil

Bio chainsaw oil

Biodegradable chainsaw oil buying guide, UK checks

Biodegradable chainsaw oil near a pond or UKWAS wood

Sources

Public UK sources and manufacturer pages, plus amazon.co.uk listing details from saved listings dated 21 October 2026. This is not a laboratory test.

  1. UKWAS, Woodland operations (retrieved 21 October 2026)
  2. Defra, Government Buying Standards for hydraulics (2015) (retrieved 21 October 2026)
  3. HSE INDG317, Chainsaws at work (retrieved 21 October 2026)
  4. Oil Storage (England) Regulations 2001, regulation 2 (retrieved 21 October 2026)
  5. Oil Care, biodegradable lubricants (retrieved 21 October 2026)
  6. Stihl UK BioPlus (retrieved 21 October 2026)
  7. LIQUI MOLY Bio Saw Chain Oil (retrieved 21 October 2026)
  8. Oregon O10-6362 biodegradable chain oil (retrieved 21 October 2026)