The three Cup cars of Joe Gibbs Racing have been found to be utilising non-approved components and ordered to switch them out for their standard counterparts.

The #11 of Denny Hamlin, #18 of Kyle Busch and #20 of Joey Logano were found to be using oil pans heavier than those routinely in use on NASCAR vehicles, which could help lower the cars' centre of gravity and improve handling characteristics.

The oil pans are not expressly illegal but have simply never been submitted to NASCAR for approval before. The irregular components were spotted during Friday morning during opening day inspection at Michigan International Speedway ahead of this weekend's Heluva Good! Sour Cream Dips 400, and NASCAR instructed the team to replace them with approved equivalents.

Because the oil pans were identified and replaced prior to the start of any on-track running, all three cars' practice times will still stand - but NASCAR will consider the matter at the post-race review early next week to determine whether any additional penalties are warranted.

The announcement comes just four days after NASCAR penalised the #18 of Kyle Busch for running the car's left front at settings lower than allowed by the 2011 NASCAR rule book at last weekend's Cup race at Pocono. Busch was docked six championship points and the team lost six owners' points; Busch's pit crew chief Dave Rogers was also fined $25,000 for the transgression, which was deemed to be accidental.

If the latest issue is deemed to be a more conscious attempt at circumventing or breaking the rules, the penalties could be significantly more serious. In 2010, Clint Bowyer lost 150pts in the Cup championship and his crew chief fined $150,000 and suspended for six races at the start of the Chase after NASCAR accused the race winning #33 of being intentionally "altered" away from specifications at the September event at New Hampshire.

By contrast, Busch's penalty for the ride height infringement last week was a slap of the wrist. In a statement accepting last week's penalty, JGR attributed it to a part failure.

"The situation was caused when the left front spring became dislodged," the team stated. "This resulted in the left front corner of the car to be lower and resulted in a change to the car's handling, which had to be compensated for during the race. Consequently, the car measured low during post-race inspection."

Last week's violation did not affect Kyle Busch's probation period for his altercation with Richard Childress Racing driver Kevin Harvick at Darlington in May. The probation period for both drivers elapsed on June 15 and so Michigan is the first race since probation ended; Harvick pointedly serviced notice at Pocono that he had every intention of continuing the feud with Busch on track, following his own and Richard Childress' recent confrontations with Busch.