The pair starred as brothers Del Boy and Rodney Trotter in the sitcom, which was a huge hit and ran from 1981 to 2003.
But Jason, 82, told Radio Times that these days the actors don't get together as much as he would like to.
“He’s much more – how can I say? – self-contained, perhaps, than he used to be," the actor said of Lyndhurst, who lost his 19-year-old son Archie in 2020 from a brain haemorrhage which occurred as a result of acute lymphoblastic leukaemia.
"So, unfortunately, we don’t see each other as much as I would like to."
"But that’s how things work out sometimes," he added.
The Darling Buds Of May star revealed that it was a blast making the comedy and that everyone working on the show was very close.
"I miss it terribly," he said. "It wasn’t like going to work; it was going to have some fun with your mates."
Only Fools And Horses was written by John Sullivan and followed market trader Del Boy and his brother Rodney as they tried to get rich.
The hit show regularly tops polls as one of the greatest British sitcoms ever made.
Seven series were originally broadcast BBC One and there were also several Christmas specials, up until the end of the series in 2003.
The comedy also starred Lennard Pearce as Grandad and Buster Merryfield as Albert Trotter.
Watch: Sir David Jason on his career highlights and acting advice