TL-Rocket

Hey Folks,

Any one know if I can start using 10W-30 Mobil 1 Synthetic (instead of 5W-20) in my high mileage TL (151K miles)?

TL- Rocket

Bearcat94

Why do you think you'd benefit from a 10W?

I hate cars

I would do a 30wt regardless of mileage, I've used it since the car was brand new.

Needing a heavier oil based on mileage is assuming you have enough wear to warrant it.

Whether you use a 10w-30 or a 5w-30 depends on which brand/type of oil you choose. Viscosity index improvers are bad. The greater the difference from the low number to the high number, the more VIIs are in the oil. A cheap base oil will require more VIIs to reach the desired hot viscosity.

A great base oil like a true synthetic such as Redline require no VIIs. Their 5w-30 is technically a straight 30wt because no VIIs are needed to hit the cold flow and hot viscosity requirements. In other words it naturally thickens less when cold and thins less when hot.

A 5w-30 will be slightly thinner than a 10w-30 when cold but it's marginal. The 5w designation is measured at -35F so at your starting temps, there won't be a whole lot of difference in a 5w and 10w-30. Since I run Redline and it uses no VIIs in either of it's 30wt oils, I go with the 5w-30 for slightly better cold flow.

If you're going to pay the price for a synthetic and want a store bought brand, you might as well use Mobil One EP. It's one of Mobil's only true synthetics despite what the labels say.

ALEXMEX

So my 2005 TL is about to hit 75,000. Its been using 5w-30 this whole time. Should i swap yes or no? I dont use synthetic yet, so should i go synthetic? I do the oil change every 3,000 without missing a beat.

GeaugaDog

if you seriously change your oil every 3,000 miles then you're doing it all wrong. follow the MID on the car and change it when it says it needs it. every 3,000 is a waste!

Gfaze

Just run whatever the car calls for from the factory and change it when the MID in the car indicates it. Every 3K is a waste of money and natural resources. I've got 135K+ miles on my car running 5W30 synthetic and I never have to add any oil between changes. I run it 7500 miles and the oil level stays the same the entire time. I've been doing it this way for 75K miles (bought used with 60K miles) and have had zero issues.

Oh and by the way, this thread --->