A MOTORING expert has revealed the eight used car red flags that should send you running for the hills - including the "mayonnaise" check.
Pete Ridley, from , urged motorists to watch out for the warning signs of a bad deal and even crafty scams.
Pete said: "Buying a used car can be a great way to save money, but it can be daunting for those who don’t know cars inside and out.
"From targeted scams, to just not knowing what is a red flag, buyers need to know what to look for, what to avoid, and how to approach a sale when looking at buying a used car."
Thankfully, the motors whizz was on hand to share his do's and don'ts and give Brits a step-by-step guide to used car shopping.
DO: Ask for a test drive
It may seem obvious but you should always take the car for a decent test drive before you agree to hand over any money.
READ MORE MOTORS NEWS
Don't just pop it around the corner for five minutes - make sure to take it through a range of speeds and through corners to test out the performance as much as possible.
Not only can this reveal any issues under the bonnet, it also gives a great idea of the feel of the car and the driving experience.
You can then decide whether it's something you actually enjoy taking out on the road, which will only mean you treasure it more.
Always be cautious of sellers who are reluctant to let you take the car out as it could suggest there is something that they don't want you to know.
Most read in Motors
As an extra bit of safety, it's also a great idea to get a mechanic to come out with you and take a look over the car before you make the deal.
The RAC offer an expert 218-point check and three-mile road test for £116, with more extensive examinations available at a higher fee.
DON'T: Meet in public
Be wary of anyone who asks you to view the car in a public place as it leaves you vulnerable to a dodgy deal, Pete warned.
Always try to make a visit to the seller's home or the place where it is being stored.
That way you can check that all the paperwork matches up with their address and get an idea of the conditions the vehicle has been kept in.
Indeed an experienced car dealer revealed that even he had fallen for a crafty scam after finding issues with where his new motor was registered.
And in terms of when to make the sale, Pete added: "You should also only ever meet in daylight.
"Not only is this safer, but any issues such as bodywork or paint damage will be harder to hide."
DO: Mind the gap
An easy thing to check is if there are any gaps between panels on the body of the car.
If these are larger than a few millimetres, their unlikely to be a design feature and could indicate that the car has been dented or even involved in a shunt.
It shouldn't be a problem if the seller is honest about why these have occurred, but if they deny it then they may well be hiding other problems.
Sellers who are cagey about answering these questions are a huge red flag.
Pete Ridley
DON'T: Ignore rust
Rust is the ultimate car killer if it's allowed to take hold.
A little bit isn't a problem and can usually be solved when caught early.
But if you see significant rust or bubbling in the paintwork (suggesting rust underneath) then don't hand over your cash.
Particular danger areas include the wheel wells, door hinges and door frames.
Getting stuck with a rust bucket could see you shelling out thousands on repairs down the line or even having to write it off.
DO: Check for "mayonnaise"
Now, if you found actual mayonnaise in your motor that would be a very weird red flag, but it is a useful way to remember how to check the condition of the oil.
Pop the bonnet and take out the dipstick to have a look for any signs of degradation.
Gritty oil, burnt smells or thick mayonnaise-like gunk on the filler cap can all indicate major issues like a coolant leak or head gasket failure.
Oil systems are notoriously expensive to fix so don't take the risk.
DON'T: Forget the smell test
So you've had a look at the car and tried it out to get a feel of it - now it's time to smell it.
Smokers and pet owners sell their cars just like anyone else but the odours left behind can take time, effort and money to get rid of.
It's not just a case of whacking an air freshener in and a deep clean could set you back over £100.
Even worse, though, is the smell of damp which can indicate mould growing in the car even if you can't see it.
If you get a whiff of the musty aroma, make sure to give the interior a thorough inspection and make sure there is nothing rotting in there.
Five tips to get the best deal when buying a used car
According Wheeler Dealers star Marc Priestley
- Look beyond the mileage - even low-mileage cars can have problems, especially if they've been in storage
- Check the tiny details - something as small as the rubber seals around doors and windows can be vital
- Have a look underneath - watch out for rust and corrosion on the underside
- Inspect the boot - watch out for damp and leaking water
- Check the papers - service history, MOT history, registrations documents
DO: Check the temperature gauge
This is a nifty trick to catch out dishonest sellers who might warm the car up for a bit in order to disguise problematic cold starts.
If the dial is already up when you get behind the wheel, either the thermostat is broken of the car has been driven before you arrived - and could be hiding an engine fault.
Make sure to get a good idea of how well it fires up to save you being stranded with a busted starter on a cold winter morning.
DON'T: Be shy
Finally, don't be timid about asking plenty of questions and making sure you get the answers you want.
Quiz the seller on things like why they have put the car on the market, its service and ownership history and the documentation hey can provide.
READ MORE SUN STORIES
Pete went on: "These questions will not only help you gauge the condition of the car but help you figure out the seller as well.
"Those who are cagey about answering these questions are a huge red flag."