Oil question

[DDKing13]

So I just got a 91 318i. When these cars came out, did they use synthetic or conventional oil?

My coworker was telling me that you can't just switch all of a sudden, if it's been using conventional.

Is there possibly a way to tell if its been running conventional oil? And if in fact it has been running conventional oil, how do I go about prepping the engine to use synthetic?

Or is that just not true? To my understanding, it doesn't matter if it's conventional or synthetic, all that matters is the weight. But I'm not super knowledgeable when it comes to engines, so I could be wrong.

Thanks in advance!

[RedReplicant]

Pour some Rotella T5 in that bitch and call it a day.

[roguetoaster]

So I just got a 91 318i. When these cars came out, did they use synthetic or conventional oil?

Conventional would be my guess from new. The first synthetic oils were concieved in the 1930s, but did not come in to standard automotive use (as blends and additives) until the early 60s, with the first API certified 100% synthetic base oil coming out in 1972.

My coworker was telling me that you can't just switch all of a sudden, if it's been using conventional.

Baloney.

Is there possibly a way to tell if its been running conventional oil? And if in fact it has been running conventional oil, how do I go about prepping the engine to use synthetic?

Generally, you will see depositing (black or brown crust/layers) in the valve cover if it has been run on conventional and abused at all. No prep required, just change the oil.

Or is that just not true? To my understanding, it doesn't matter if it's conventional or synthetic, all that matters is the weight. But I'm not super knowledgeable when it comes to engines, so I could be wrong.

Thanks in advance!

Yes, although the formulations have changed a lot over the years since E30s were made you can safely use either type of oil, or a blend if you wish. As long as you remember that it is a flat tappet design, and as such an oil with a higher level of ZDDP may help, or it might do nothing, or it might cause your engine to implode.

Also, as to weight, follow the chart in the manual, or use heavier when hot, lighter when cold. Further, if your engine leaks a lighter oil may make those leaks worse, whereas a heavier oil may slow or prevent some of them.

If you really want to know more just go to http://www.bobistheoilguy.com/, then come back and post what you learned.

[DDKing13]

^Very helpful info! Thanks man! :up: