Thousands of people have started to flock to the western Sydney home of a Catholic couple where oil and ash have started to appear on the walls of the bedroom of their late son who was killed in a car crash last year.

The Daily Telegraph quotes Antiochian Orthodox Archbishop Paul Saliba as saying that people who think the house is a hoax should see it first before casting judgment.

Archbishop Saliba told the paper that God had many ways of revealing himself and he had no doubt that was what was happening in Guildford, in Sydney's west.

"I've been there many times and we cannot pinpoint exactly what's happening. It is miraculous," Archbishop Saliba was quoted as saying.

The Archbishop's words echo the sentiments of a local Catholic priest, Fr Michael Melhen, who told Today, Tonight that while he cannot speak on behalf of the Catholic church, as an individual believer, he is stunned at what he has seen.

The Seven current affairs program says that Fr Melhen is using the oil that comes through the walls to anoint people.

"The purpose of the oil, according to the church, is to bless people and that's a sign, a symbolism of peace," Fr Melhen said.

Mike Tannous, 17, was killed instantly after he lost control of his car and crashed just 200m from his family home on 9 September last year.

His father George yesterday told the Telegraph his wife Lina first spotted the oil on their son's bedroom wall 40 days after his death.

"My wife saw something shining on the wall like a diamond over his bed," he said.

"Only my wife saw it and there were 15 of us in the room with her. She touched it and all of a sudden oil started appearing on the walls and it hasn't stopped. This is a big miracle. I can't explain it."

Mr Tannous said two weeks before his death, Mike, a Year 11 student, dreamed he had died and was shown heaven by the Virgin Mary.

"My son always believed in God. He always had God in his heart," Mr Tannous said.

Not "typical" Catholic signs

Meanwhile, University of Western Sydney expert on the psychology of the paranormal and supernatural, Dr Tony Jinks told the Parramatta Sun that "There is a deeper story here than whether its true or a hoax".

"There are more fascinating degrees of interpretation than those two extremes. I think if people weren't highly religious these events would be put down to poltergeist activities.

"The symptoms are not uncommon but are usually associated with poltergeists, not religion these signs don't come across as typical Catholic signs, such as the bleeding Virgin Mary, and there's no stigmatism within the house.

"But I've seen a lot of things to make me very wary of saying that there's nothing to it."

But David Reardon, a graduate of the Catholic Institute of Sydney, who has studied theology and philosophy, said people were quick to assume these were signs from God.

"I'm against the business about something wonderful happening here and all these people flocking to see it," Mr Reardon said.

According to Today, Tonight, the house is at 6 Bowden Street, Guildford, NSW. Visiting hours are strictly 12-2pm and 4-6pm "only".