Synthetic oil wwhhhhaaaaaaA?

[CorvallisBMW]

I've always run Mobil 1 15w-50 in my car. I would have to top off about 1 quart between 6 month change intervals. About 1.5 years ago though, after reading much about the subject here on R3v, I decided to try Castrol GTX high mileage 20w-50 and see how the car did on the good ol' dinosaur oil. Many people said that synthetic was a waste on these old, simple engines and that the HM stuff had better conditioners and was cheaper and blah blah blah.....

Fast forward to about 4 months ago. I was refilling oil like crazy with the GTX. I had to put in about 1 quart per 4-6 weeks. I also noticed that the car didn't run any better, in fact it may have been a bit worse/more noise from the engine. So I decided to go back to Mobil 1. Low and behold, I hardly loose any oil now! It's been 4 months and I've only had to add about 0.5 quarts to keep the level near the top line on the stick. Weird. Car runs much smoother too, seems a lot happier. I always thought synthetic was much more susceptible to burnoff/leaks but I seem to have encountered just the opposite.

/end conundrum

[TwoJ's]

That's interesting. How many miles did you drive with the synthetic before going to the castrol? And how many miles are on your motor?

[UNHCLL]

6 month oil changes?

Oh boy.

[nando]

my engine is much happer with mobile 15w-50, the old stock one would choke on the stuff though. Aside from my squeaky ass belts my engine is as quiet as I've ever heard from an M20.

[teamgtnfx01]

should i use synthetic and i heard so many good things about royale purple oil

[LivingLegend06]

My M42 seems to run more quiet and smoother on synthetic. I use Royal purple 10w-30 and the only problems I had with losing any oil was from the hole I put in my oil pan.

[02stu]

Normally its the opposite most people find that synthetic oil is more likely to leak.

[Julien]

I've always ran mobil1 15w50 in my m20s and have always been happy with the results..

[krans]

I run 20w50 in my m20 and its been fine since the last oil change. Maybe i should try 15w50.

[george graves]

I've always ran mobil1 15w50 in my m20s and have always been happy with the results..

[CorvallisBMW]

6 month oil changes?

Oh boy.

I only drive about 8K miles per year so yes, 6 month changes.

[CorvallisBMW]

That's interesting. How many miles did you drive with the synthetic before going to the castrol? And how many miles are on your motor?

I ran synthetic for about 40K before switching to GTX (about 4 years). The motor currently has about 220K

[smonkbmw]

ran the castrol that bmw sells at the dealership, forgot the weight. in my swap car. seemed to do well, lol, didnt have the car long enough to change the oil in it.

[CorvallisBMW]

I know synthetic is the 'better' choice, but the main point of the post was to point out the difference in oil loss. Synthetic is always blamed for more burnoff/leaks, but I found just the opposite to be true.

[AlarmedBread]

No, you misunderstood. If you switch from dino to synthetic, you'll probably be fine, it might just remove some deposits etc. too. The problems with leaking come from switching back to dino again. Once you go synthetic, you're stuck. What you experienced is the norm. Also depending on what you got, ZDDP may have been nearly non-existent.

For my money, dino + gm zinc additive = sewing right along