I just bought a new 4 cyl Malibu. It supposedly analyzes driving conditions and tells me when to change oil. The manual makes no mention of synthetic oil but I assume it is OK to use if not better. However, I doubt if the car knows what oil is in there and it would tell me to change the synthetic sooner than necessary making it much more expensive than conventional oil. I guess I could go back to the old sticker-on-the-door method to remind me but I’d rather let the car tell me. What is a safe interval for synthetic?
To keep your warranty in force, you have to change it no later than when the reminder tells you to. You can’t go extra miles because you’re using synthetic.
Have you checked the owner’s manual? Even if it’s not listed, you could try calling one of the numbers listed in the manual and asking-- maybe there’s some rule of thumb for synthetic oil changes. I will say, though, that the GM oil change computer things are pretty nice and for most driving conditions, you’ll be extending your oil change interval a lot further than you would doing set intervals. So, in other words, I wouldn’t really want to go much further than they tell you to, synthetic or not.
The reason there’s no mention in the owners manual about the use of synthetic oil in the engine, or at what interval to have it changed is because the auto manufacturer doesn’t care what type of motor oil you use. You change it the mileage they recommend. That’s because no matter what type of oil you use in the engine, it’s going to become just as contaminated from combustion by-products. And that’s the reason for changing the oil. To remove these combustion by-products.
Now if you want a more stable oil under severe conditions, such as extreme heat/cold, high RPM’s/racing, heavy towing, or if the engine is turbocharged, the a synthetic oil is ideal.
Other than that, using a synthetic oil where the application doesn’t require it is a waste of money IMO.
My GM Cars Owner’s Manuals Recommend Synthetic For Extremely Cold Weather.
If you live in an area of extreme cold, where the temperature falls below -20F (-29C) it is recommended that you use either an SAE 5W-30 synthetic oil or an SAE 0W-30 oil. Both will provide easier starting and better protection for your engine at extremely cold temperatures."
Extremly cold weather? Lately where I live 20F is more like a daytime high and -25F is the nighttime low. Since 5W-30 is recommended even for temps above 100F, I use 5W-30 Synthetic all year long.
You can’t beat synthetic oil. As far as the change interval, I would say that if your wanted to play it absolutely, without a doubt safe, then change your oil when the oil monitor says so. However, one of the advantages of synthetic oil is that that you can extend your mileage between oil changes. I am now in the throes of an experiment on my 2001 Chevy Silverado truck. I changed the oil at 2500 miles to synthetic in the weight recommended by GM, and every 10,000 miles after that. I use a high quality oil filter (Mobil 1) and a full sythetic oil - again Mobil 1. I now have 170,000 miles on the truck and the engine still runs like it was new, with oil usage about 1 quart every 10,000 miles (which is a slight increase from when it was new).
In Europe, the oil change intervals are about double what they are in the USA, but they use synthetic oil. Whatever you do, use synthetic oil after the first oil change (this will allow your rings to seat better - I think I changed to synthetic too soon, so the rings didn’t seat properly, hence the oil usage since it was new). This is my humble opinion.
The interval is the same if you use synthetic or dino oil. The main benefits of synthetics are cold weather/startup performance and high temp stability. Although you will hear it touted, extra long change intervals (while possible in some cases) are not recommended. With that said the oil monitor in GM cars is pretty good, and you won’t hurt anything by going by it.