When Should One Switch to Synthetic?

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Jun 25, 2003
Seattle, WA
I apologize if this is a repost.

In short, I just picked up my new '03 Nissan 350Z Track last night and was wondering when is the appropriate time to switch to synthetic, if at all. My BMWs came from the factory with synthetic so I never had this question before. The break-in mileage for the 350Z is 1100-1200 miles and I plan on ultimately running the same oil that I run in the BMWs, AMSOIL Series 2000 0W-30. I was thinking of doing an oil change (including filter) after the break-in period around 1200 miles using the OE oil, then at 3500 miles (OE oil again), 7000 miles (OE oil still) and then switching to the AMSOIL around the 10k mile oil change.


350Z awaiting switch to synthetic

[ June 26, 2003, 02:32 PM: Message edited by: JawKnee ]
I would change oil and filter after the first long run with fully synthetic oil of your choice and OEM filter. I have never understood the reasoning behind running dino or semi-synthetic during the break in period, I believe the only factor that affects break-in is driving style and being in sympathy with the motor.
Good look with your new car.
Nice car! Is it that nice orange color? I saw one of them last week in a convertible (must've been aftermarket, since I don't think Nissan makes them that way)

If it doesn't come with synthetic already, just do one oil change at 500 miles with conventional oil, then do a second change around 2000 or 2500 and go to synthetic then. The extra oil changes are going to help get any excess break in material out of there.
Define hard??

Run it under varied conditions. (avoid long idles, avoid long constant highway speeds)

I'd stomp on it from time to time, but I wouldn't take it to redline.


Originally posted by DockHoliday:
Regarding break in:

Some people argue to run an engine hard during break in. Anyone agree with this concept?


If it doesn't come with synthetic already, just do one oil change at 500 miles with conventional oil, then do a second change around 2000 or 2500 and go to synthetic then. The extra oil changes are going to help get any excess break in material out of there.

That's exactly the procedure I've done since purchasing our 2004 Sienna. After the first dealer oil change @ 3k miles I left the dino oil in the engine for about 600 miles and then drained it out and put in Mobil 1 5w30. This may sound too costly for some but my plan is to have the dealer do my oil changes to keep up with the warranty after which right after I will drain and replace with synthetic oil + 3 oz. maintenance dose of Auto-RX and run with it for about 5k miles. I'll have better peace of mind knowing that it's synthetic oil in the engine and not some unknown batch of oil plus in the dealer's books I'm keeping up with the warranty by having them do the oil changes.
Doc, I recently read about agressive breakin. The article recomended this for 20 miles. My car had 8 miles when I picked it up so I did the agressive breakin for the next 12 miles. I then drove easier but more agressive then I would normaly drive dureing break in for the next 38 miles. I drained the oil at 58 miles and refilled.I am now driveing it normal. We will see in about 150,000 miles how much difference it makes. The article I read said that you only have about 20 miles to seat the rings and that after that you are S.O.L.!!! P.S. You do not have to drive it hard for 500 miles. It is just a 20 mile hard breakin. Basicly after you are in 2nd or third gear you want to do some 3/4-WOT acceleration pass's often dureing the first 20 miles.

[ June 26, 2003, 06:43 PM: Message edited by: JohnBrowning ]
Does anyone have a link to this article? What do the authors of this article know that the engineers, designers, and builders of every automobile engine in the world don't? They all have a recommended break-in period, during which no high-revving or loading should be done.

Castrol (set your own "trust level") says that you can change right away to synthetic and you mentioned that Bimmers come with it from the factory (as do Porsches, most, if not all Mercedes [not just Mercedes AMG], Aston Martins, Corvettes, and Vipers. What I don't know is, have ALL these OEMS manufactured their engines with synthetics in mind, specifically to be "broken in" on synthetics. I used to follow a routine similar to what you are describing that you intend to do (although planning to switch sooner than 10K); but on my next new vehicle purshase (hopefully this Fall), I intend to do a change at 500, 1500 and then synthetic at 3000. The only reason I am not putting a synthetic in sooner is due to the short oil change intervals.

Synthetics are "slicker" and cause the lengthens the time for the rings to seat. I cannot speak for the foreign cars......but corvettes have a "rough" hone to the blocks that allow the rings to seat and wear-in, even with synthetics. The initial fire up and break in in done at the factory. I have done the initial break-in to several engines I have built myself. Speaking from my experience and the experience of enginebuilders that I know, I would not run the engine hard for at least 1000 miles. Just vary the rpms and load condition and do not idle for extended periods.

[ July 08, 2003, 09:01 PM: Message edited by: sbc350gearhead ]
When breaking in my 01 F-150, I changed the break-in fluid at 1000 miles. I used the Motorcraft 5W-20 oil for the next 1000 miles, then changed it out to a cheap synthetic (Valvoline). At 3,000 miles I changed to Red Line 10W-30 and have been using that excluisively for the past 17,000 miles. I have had no problems, and the interior of the engine is clean enough to eat off of. I changed the filter every 500 miles for the first 3000 miles.

[ July 08, 2003, 11:50 PM: Message edited by: mf150 ]
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