Easy start doesn't cause much smoke. White/grey smoke is usually unburnt diesel, but don't take my word for it - take a sniff, you'll soon see lol. The other option is oil burning off in the exhaust, but that isn't relevant in this case as your exhaust won't be hot enough.
Edit: Tbh whatever it is it doesn't sound like it's worth the effort for an extra £50...
Edit: Tbh whatever it is it doesn't sound like it's worth the effort for an extra £50...