What kind of engine oil

Tiny
KHIDREAL
  • MEMBER
  • 1998 PEUGEOT 306
  • 1.8L
  • 4 CYL
  • 2WD
  • MANUAL
  • 155,000 MILES
In a form of general question that suits everybody with an old car, is there any problem on using modern motor oil, specially regarding the technology and viscosity that did not exist by the time the car was manufactured?
How old can a car be to, as of 2018, be compatible with modern motor oil?
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Wednesday, November 7th, 2018 AT 1:48 AM

4 Replies

Tiny
CARADIODOC
  • EXPERT
Dandy question, but your concern should be for going the other way and using old oil you have sitting in your garage in a newer engine. In the U.S. There are two ratings to look at on the container. One is something like "SG" and the other is "CD".

The "S" in that rating stands for "spark ignition", meaning a gas engine. The "C" in the other rating is for "compression ignition" meaning diesel engines. Engine manufacturers specify the minimum rating required for their engines, and that will be something that is currently available. Whenever a major improvement is made regarding the additives in the oil, the rating gets bumped up to the next second letter. That means an oil with a rating of "SG" has some improvement over an oil with a rating of "SF". Oil produced with the next significant upgrade will be rated "SH". You can use any oil with a rating higher than what was the best the year your engine was produced. If your engine calls for "SE", for example, you can use "SF", "SG", and whatever is higher than that. You probably should not use "SC" or "SD". If you still have some of that, it probably would not hurt to use one container at a time during an oil change to use up your stock. You will not find the older oils in an auto parts store. They always have oil with the current highest rating. An oil that is advertised as being for older engines or high-mileage engines will have more of some additives such as seal conditioners, but those will still work fine in engines that call for that rating.

The additives in question include things like anti-foaming agents, corrosion inhibitors, seal conditioners, dispersants, detergents, and viscosity index improvers. Many people seem to have a bigger problem when they switch brands of oil. Each brand has its own proprietary list of additives that work well together, but some may not be compatible with some additives in another brand of oil. For example, the seal conditioner in the old oil might be attacked by the detergent in the new oil. That could result in a leaking seal. When you drain and refill five quarts of oil during a normal oil change, there is actually about seven quarts of oil in the engine. Two quarts is stuck in the passages and bearings and that does not drain out. That means you still have two quarts worth of old additives after the oil change that may not be totally worn out and ineffective yet.
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Wednesday, November 7th, 2018 AT 3:02 PM
Tiny
KHIDREAL
  • MEMBER
CARADIODOC many thanks to you sir.
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Thursday, November 8th, 2018 AT 4:35 AM
Tiny
KEN L
  • ADMIN
CARADIODOC is one of our best! Use 2CarPros anytime, we are here to help. Please tell a friend.

Cheers, Ken
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Saturday, November 10th, 2018 AT 11:17 AM
Tiny
KHIDREAL
  • MEMBER
  • 1998 PEUGEOT 306
  • 1.8L
  • 4 CYL
  • 2WD
  • MANUAL
  • 155,000 MILES
So I am still struggling to find solution to my oil problem.

My car probably always used 10W-40 as it is like what 99% of mechanics in my country put to your car.

I came to a shaddy list on the internet saying the recommended oil for my car was 15W-40, and I changed it to it, gradually, I had an oil leak and I just started adding the 15W-40 as the 10W-40 would leak.

Conclusion is that my car struggles to cold start honestly, very loud on the first ten seconds and the throttle just goes crazy on the first four seconds going up and down as the engine tries to lubricate itself. So bad choice on putting the 15W-40.

So now I need to change it again. My questions would be, what oil to use on this twenty year old car. It is fully mechanical and the engine heats a lot during summer.

I got recommended by a guy (not a mechanic) to use Petronas Synthium 7000 0W-40, he says it is a lot more fluid providing better cold starts and much less struggle, while providing the same density when the engine is hot as my current oil. He also says its additives will help the engine cool down a lot more and take better care of the engine.
Then I go to a mechanic and he says that oil is better for trucks.

So problem right now is I do not know what oil to use. The car is old and I would like an oil that takes care of the engine better as I really like this car and I want to drive it for many years.
Oils thicker than 10W-40 is not in question, I cannot use them. I can use 0W40, 5W40 or 10W40.

When the car had 10W40 it still struggled a bit to cold start but it was okay.
But my idea is to give the least effort for my engine to start, but before breaking my engine I would like to know what others with knowledge on the matter say.
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Saturday, December 8th, 2018 AT 4:37 PM (Merged)

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