You should use synthetic oil instead of conventional oil as synthetic oil can make your engine last longer.
Using synthetic oil is better for your engine than conventional oil.
Although conventional oil (i.e., mineral oil) can provide adequate lubrication performance, it can't compete with the overall engine performance and protection provided by synthetics.
Most high mileage oil is a synthetic blend of oil.
However there are some high mileage oils that are not synthetic but most high mileage oil is synthetic.
High mileage oils are usually synthetic oils.
They are typically based on either full-synthetic oil or a blend of synthetic and conventional oil.
If you have over 75,000 miles on your modern car or truck, consider switching to a high-mileage motor oil.
These are a blend of synthetic and mineral-based oils with extra detergents added to them.
The high mileage oil is designed for vehicles with more than 75,000 miles on them.
Synthetic oil is generally required for new cars as a rule of thumb.
The conventional oil in older cars generally runs well, unless your vehicle has more than 75,000 miles on it, in which case you should use high-mileage oil.
Most vehicle manufacturers would say it's normal for an engine to consume some oil between oil changes.
In addition to having seal conditioners, high-mileage oils usually boast more detergents designed to clean out sludge inside the engine, plus other additives meant to reduce wear on moving parts.
You can use a blend or rotate between a full synthetic and non-full synthetic every other oil change if synthetic oil is too expensive.
Synthetic oils typically provide better protection than conventional oils, but switching back and forth between full synthetic and conventional oil will not damage the engine.
There is no danger mixing synthetic and conventional motor oil.
However, conventional oil will detract from the superior performance of synthetic oil and reduce its benefits.
Synthetic blend oil is a mix of conventional motor oils and synthetic base stocks.
Because of the added synthetic base stock, you're going to get more performance and protection than you would by using a conventional oil alone.
The oil does not harm and it can prevent leaks from starting if it is used at a high mileage.
It is recommended by some mechanics to switch to a thicker (higher viscosity) oil – such as 10W-30 full synthetic oil instead of 5W-20 full synthetic – or to use oil additives to prevent leaks from occurring.