The M6 in Preston has reopened for rush hour with just two lanes, but will close again for resurfacing this evening.
The southbound carriageway between 32 and 31A had been shut since 9.15am before partially reopening at 3pm.
It will remain open for rush hour, before a total closure resumes between 8pm and 5am for resurfacing.
Highways are warning motorists to brace themselves for journey times up to 90 minutes longer than usual during rush hour.
A Highways spokesman said: "The M6 has reopened at #J32 #Broughton #M55 southbound with lanes 1 and 2 still closed for the spillage clean up.
"But please be aware that severe delays remain on approach to J32, with 10 miles of very slow moving traffic.
"Average journey times are an hour and a half longer than normal for this time of day.
"Allow plenty of extra time for your journey if you're travelling in the area.
"There will also be a total closure between junctions 32 to 31a from 8pm to 5am.
"It will be the same diversion as today.
"All 4 lanes need resurfacing due to diesel damage with damaged sections as long as 300 metres."
It follows a huge fuel spillage this morning in which 200 litres of diesel leaked across a half-mile of carriageway near junction 31a.
A lorry transporting heavy plant machinery jackknifed on the M6 at around 9.10am, overturning its contents onto the carriageway.
Highways immediately closed all M6 southbound lanes between junction 32 (Broughton, A6, Blackpool, M55) and 31a (Preston, Longridge) to deal with the incident.
For more information on today's M6 closure and diversions, you can read our earlier coverage below:
Miles of trapped traffic was freed using the hard shoulder to pass the scene under the supervision of traffic officers.