Oliver, 12, who lived with his family in Louth, was involved in the collision in Kirklington, near Newark, on Saturday December 1.
He was taken to Queen’s Medical Centre in Nottingham with serious head injuries.
However, after more than a week in hospital, on Tuesday this week (December 11), Oliver sadly passed away.
Oliver’s sister, Cerys, told the Leader: “Oli was a lovely, caring, funny, cheeky young lad that was loved by all.
“As a family, we would like to say a huge thank you to the staff at Queen’s Medical Centre in Nottingham, specifically those working within the Paediatric Critical Care Unit which treated and looked after Oli.
“The staff were absolutely incredible, both the doctors and nurses deserve recognition for their services. They all went above and beyond their duties.
“We would also like to recognise the efforts of the Lincs & Notts Air Ambulance crew that transported Oli to the hospital following the accident.
“Oli is continuing to make family and friends proud, as our little hero has also donated his organs to those children in need.
“He always told us he wanted to become an organ donor and help others one day.”
Oli leaves behind his mother Alison Welby, stepdad Mark Wain, sister Cerys Meredith (20), and brother Riaan Armstrong (13).
Cerys added: “For those who knew Oli, on Monday December 17, his friends from Louth Academy have organised a meet-up to let off balloons in memory of him.
“All friends, family and any one that knew Oli is welcome to join. This will be held at Brackenborough Park from 3.30pm to 4.15pm.”